[2] Matthioli Opera, Ed. 1598, p. 8, originally published 1565.

[3] Ray's instances relate to Kales, and in most of these examples we can see that there was no question of mutation or transmutation at all, but that the occurrence was due either to mistake or to cross-fertilisation. Sharrock, to whom Ray refers, was inclined to discredit stories of transmutation, but he has also this passage (History of the Propagation and Improvement of Vegetables by the Concurrence of Art and Nature, Oxford, 1660, p. 29):

"It is indeed grown to be a great question, whether the transmutation of a species be possible either in the vegetable, Animal, or Minerall Kingdome. For the possibility of it in the vegetable; I have heard Mr. Bobart and his Son often report it, and proffer to make oath that the Crocus and Gladiolus, as likewise the Leucoium, and Hyacinths by a long standing without replanting have in his garden changed from one kind to the other: and for satisfaction about the curiosity in the presence of Mr. Boyle I tooke up some bulbs of the very numericall roots whereof the relation was made, though the alteration was perfected before, where we saw the diverse bulbs growing as it were on the same stoole, close together, but no bulb half of the one kind, and the other half of the other: But the changetime being past it was reason we should believe the report of good artists in matters of their own faculty."

Robert Sharrock was a fellow of New College, Oxford. Both the Bobarts were professional botanists, the father was author of a Catalogue of the plants in the Hortus Medicus at Oxford, and the son was afterwards Curator of the Oxford Garden.

[4] MÉm. Ac. roy. des Sci. for 1719 (1721), p. 59.

[5] Amoen. Acad., 1789, vol. 6. I do not know whether attention has been called to the curious mistake which Linnaeus makes in the course of this argument. He cites the differences between the Mule and the Hinny in illustration of his thesis, pointing out that the Mule is externally more like a horse and the Hinny more like an ass. This, he says, is because the Mule has the horse for a father, and the Hinny the ass, thus inverting the actual facts!

[6] Proc. Washington Ac. Sci., 1909, XI, pp. 17-26.

[7] J. W. Tutt, in Ent. Rec., 1909, XXI, p. 185.

[8] E. Lehmann (Bull. l'Herb. Boissier, Ser. 2, VIII, 1908, p. 229) has published an admirable paper on the interrelationships of these species and has instituted cultural experiments which will probably much elucidate the nature of their specific distinctness. As regards the existence of intermediate forms he comes to the conclusion that two only can be so regarded. The first was described by Kuntze from specimens found on a flower-pot on board a Caspian steamer, from which Lehmann proposes the new specific name Siaretensis. This comes between polita and filiformis, a close ally of Tournefortii. The other, which combines some of the features of both polita and Tournefortii, was found in the province of Asterabad.

[9] In Cambridgeshire for example vespertina is common but diurna is absent. Whether this absence is connected with the general presence of chalk I cannot say. When introduced artificially diurna establishes itself, for a time at least, without any apparent difficulty and occasionally escapes from the garden on to the neighbouring roadside.

[10] Conceivably however it may be a segregated combination. For an account of this plant see Boissier, Voy. Bot. Midi de l'Espagne, 1839, II, 722.

[11] A discussion of this subject with references to literature is given by Rolfe, in an excellent paper on "Hybridisation viewed from the standpoint of Systematic Botany" (Jour. R. Hort. Soc., XXIV, 1900, p. 197). He concludes: "The simple fact is that the two plants (L. diurna and vespertina) are thoroughly distinct in numerous particulars, and affect such different habitats that in some localities one or the other of them is completely wanting. But when their stations are adjacent they hybridise together very readily, and it is here that these intermediate forms occur which have puzzled botanists so much." The same paper contains valuable information concerning several cognate illustrations.

[12] In only two cases have I seen such plants (both females) completely sterile.

[13] As is well known, in an even more notorious example, he proposed to unite Primula vulgaris, P. elatior, and P. acaulis, similarly relying on the existence of "intermediates," which we now well know to be mongrels between the species.

[14] For an account of the distinctions between Vespa vulgaris and germanica see Ch. Janet, Études sur les Fourmis, les GuÊpes et les Abeilles, 11^e, Note. Sur Vespa germanica et V. vulgaris. Limoges (Ducourtieux), 1895; and R. du Buysson, Monographie des GuÊpes, Ann. Soc. Ent. France, 1903, Vol. LXXII, p. 603, Pl. VIII.

[15] The statements made above are for the most part taken from Barrett, C. G., Lepidoptera of the British Islands, and from Tutt, J. W., The British Noctuae and their Varieties. The reader who is unfamiliar with the amazing polymorphism exhibited by some of these moths should if possible take an opportunity of looking over a long series in a collection, or, if that be impossible, refer to the admirable coloured plates published by Barrett. It may not be superfluous to observe that plenty of similar examples are known in other countries. For instance Plotheia frontalis, a Noctuid which often abounds in Ceylon, shows an equally bewildering wealth of forms. If a dozen specimens of such a species were to be brought home from some little known country, each individual would almost certainly be described as the type of a distinct species. (See the coloured plate published by Sir G. Hampson, Cat. Brit. Mus., Heterocera, Vol. IX.)

[16] Dict. of Birds, p. 800. It would be interesting and profitable to attempt in a long series of Ruffs to determine the Mendelian factors which by their combinations give rise to this complex assemblage of varietal forms. A few such factors both of colour and pattern can be at once distinguished, and it is noticeable that some of the resulting types of barring, spangling and penciling show a perceptible correspondence with some of the types of colouration found in the breeds of domestic fowls.

[17] Howard Saunders (Illust. Manual of British Birds, 1899, p. 499) states that there is evidence that the pheasant had become naturalized in the south of England before the Norman invasion. He adds, "little, if any, deviation from the typical P. colchicus took place up to the end of last century, when the introduction of the Chinese Ring-necked P. torquatus commenced, which has left almost indelible marks, especially with regard to the characteristic white collar."

[1] In saying this we make no assumption as to the particular cell-division at which differentiation occurs. This may be one of the maturation-divisions, or it may perhaps be much earlier.

[2] From the recent discoveries of Erwin Baur we are led to surmise that in the flowering plants the sub-epidermal layer, or some of its elements, may legitimately be regarded as a similar germ-substance, continuous in Weismann's sense.

[3] These fraternal twins, which show no special resemblance to each other, are like the multiple births of other animals, and there is no disposition for them to be of the same sex. In the sheep, for example, statistics show that the frequency of pairs of twins, male and female, is approximately double that of the frequency of pairs, both male or both female, as it should be if the sex-distribution were fortuitous. For instance Bernadin (La Bergerie de Rambouillet, 1890, p. 100) gives the following figures for twin-lambs in Merinos: both male, 87; both female, 83; sexes mixed, 187. The 9-banded Armadillo (Dasypus novemcinctus), in which the young born in one litter are said to be always of one sex, is the only known exception in Vertebrates, and is presumably a genuine case of normal polyembryony (see especially, Rosner, Bull. Ac. Soc. Cracovie, 1901, p. 443, and Newman and Patterson, Biol. Bull., XVII, 1909, p. 181), and an important paper lately published by H. H. Newman and J. T. Patterson, Jour. Morph., 1911, XXII, p. 855.

[4] A good collection of evidence as to disease in homologous twins was lately published by E. A. Cockayne, Brit. Jour. Child. Diseases, Nov., 1911.

[5] Cp. Windle, B. C. A., Jour. Anal. Phys., XXVI, p. 295.

[6] Mr. E. Nettleship tells me that in the course of collecting pedigrees of families containing colour-blind members he has discovered two cases (shortly to be published) of pairs of twins, which on account of their very close resemblances must be deemed homologous, one of each pair being colour-blind and the other normal. Such a distinction between closely similar twins is most curious and unexpected.

[7] Another paradoxical phenomenon of the same nature occurs in the Narwhal The males normally have the left tusk alone developed, the corresponding right tusk remaining as an undeveloped rudiment in its socket. The left tusk is a left-handed screw. Occasionally the right tusk is also developed and grows to the same length as that of the left side, but in such specimens the right tusk is also a left-hand screw like the tusk of the other side, instead of being reversed as we should certainly have expected. It need scarcely be remarked that in the case of the horns of antelopes, and in other examples of spiral organs arranged in pairs, that of one side of the body is the mirror image of that on the other side. The Narwhal's tusks in being both twisted in the same direction are thus highly anomalous, and are comparable with pairs of twins.

[8] Wilder, H. H., Amer. Jour. Anat., 1904, III, p. 452.

[9] Polydactylism which is often a dominant and the web-foot of Pigeons which is recessive should be remembered as possible exceptions (see p. 49).

[10] Davenport inclined at first to regard rumplessness as a recessive, but in his latest publication on the subject he definitely concludes that it is an imperfect dominant. This conclusion accords well with evidence quoted by Darwin (An. and Plts., II, ed. 2, p. 4) that rumpless fowls may throw tailed offspring. (Amer. Nat., 1910, XLIV, p. 134.)

[11] Spillman, W. J., Amer. Breeders Mag., 1910, I, p. 178.

[12] Newsholme, Lancet, December 10, 1910, p. 1690.

[13] Materials for the Study of Variation, 1894, p. 358.

[14] Walker, G., Johns Hopkins Hospital Bulletin, XII, 1901, p. 129.

[15] Cp. R. H. Compton, New Phytologist, 1911, p. 249.

[16] Arch. f. Entwickelungsmech., 1907, XXIII, p. 249.

[17] Bull. Soc. Bot. de France, xxxiv, 1887, p. 182.

[18] R. Boyle, The Origine of Formes and Qualities, Oxford, 1666.

[19] Remarkable experiments on this question have lately been carried out by R. H. Compton (Camb. Phil. Soc., XV, 1910, p. 495), showing that in a certain Barley, "Plumage Corn," the average ratio of left to right is about 1.5. A fuller paper has since been published by Compton, Jour. Genetics, 1912, II, I, p. 53.

[1] StÉphane Leduc, ThÉorie Physico-Chymique de la Vie, Paris, 1910.

[2] Materials for the Study of Variation, No. 249, p. 217; and p. 272.

[3] Materials, p. 118.

[4] Church, A. H., On the Relation of Phyllotaxis to Mechanical Laws, London, 1904.

[5] It is a question whether the dominance of the palmatifid leaf over the pinnatifid is not really an example of the dominance of a lower number of segmentations over a higher. From the uncertainty whether two given leaves of two separate plants are actually comparable one cannot institute quite satisfactory numerical comparisons, but I think the view that the "Fern" leaf has more lobes than an otherwise similar "Palm" leaf may be fairly maintained. If this be admitted, the "Palm" leaf represents the dominant low number and its round shape is a consequence of the greater powers of growth which are so often possessed by the members of a shorter series.

[6] It is perhaps of importance to remember that in certain species of bacteria (e. g. Bacillus Anthracis) division may cease where the organism is cultivated under certain artificial conditions though growth continues. In this way very long unsegmented threads are produced.

[7] Arch. f. Entwm., XX, 1905, p. 76; Sitzungsb. d. Ges. Naturf., Berlin, 1907, p. 41, etc.

[8] Borradaile, L. A., Jour. Marine Zool., 1897, No. 8.

[9] Dr. Przibram, I should mention, concludes that on the whole the facts are against this interpretation, but as more evidence is certainly required, I call attention to the possibility.

[10] Morgan, T. H., Regeneration, 1901.

[11] It would be interesting to know whether growth continues at the original posterior end after the new "posterior" end has been formed in front.

[12] In the actual case observed, the ripples unsmoothed had a wave-length of about 2-1/2 inches; and when the new ones were first formed, there were about 30 ridges in the length originally traversed by 15 or 16.

[13] The Science and Philosophy of the Organism; Gifford Lectures, 1907. London, 1908, p. 141.

[1] Gates, R. R., Zts. f. Abstammungslehre, 1911, IV, pp. 341 and 361.

[1] See Lotsy and Baur, Rep. Genetics Conf., Paris, 1911, pp. 416-426. Compare Lecoq on Mirabilis jalapa × longiflora, FÉcondation des VÉgÉtaux, 1862, p. 311.

[2] Rep. Evol. Ctee. R. S., IV, 1908, p. 38.

[3] Ber. Deut. Bot. Ges., 1908, XXVI, a, p. 672.

[4] Jour. Genetics, 1, 1910, p. 57.

[5] In Rep. 1 to Evol. Committee, 1902, p. 132, attention was called to this possibility, though of course at that date it was in sexual animals alone that it was supposed to exist. It had not occurred to me that even a hermaphrodite plant might be in this condition.

[6] From the description of the offspring of muricata used as mother.

[7] de Vries, Species and Varieties, 1905, p. 259.

[8] Zeijlstra in a recent paper announces that many nanella plants are the subject of a bacterial disease to which he attributes their dwarfness. I gather that this does not apply to all nanella plants and that some are dwarfs apart from disease. The matter may no doubt be further complicated from this cause.

[9] Zts. f. Abstamm., 1912, VIII.

[10] Arch. f. Zellforschung, 1912, IX, p. 331.

[1] For the evidence see Tutt, J. W., Trans. Ent. Soc., 1898, p. 17. Compare the remarkable case given by Gulick (Evolution Racial and Habitudinal, p. 123) of the two races of Cicada, which are separated by reason of their life-cycles, one having a period of 13, the other 17 years.

[2] For references see Materials, p. 396, and also G. Baur, Amer. Nat., 1893, July, p. 677.

[3] Jenner Weir, Entomologist, 1880, XIII, p. 251.

[4] Jentink, Notes Leyden Mus., 1885, VII, p. 111. Specimens illustrating this peculiarity are in the British Museum.

[5] Proc. Zool. Soc., 1895, p. 850. Plate. Many points beyond that mentioned above are involved in this remarkable case. For example, not only are there males like females, but a small proportion of females resemble the ordinary male type. The stripes are not merely the spots produced, for they occupy different anatomical positions. The spots almost always go with a black ventral surface, but the striped forms nearly always have that region testaceous. Spartium retama, the food-plant, will not grow in England, but if it could be naturalised in America the whole problem might be investigated there and results of exceptional interest would almost certainly be attained.

[6] Doncaster, L., Proc. Zool. Soc., 1905, II, p. 528.

[7] I am not aware that the details of this striking case have ever been worked out. It should be noted that the green and blue forms are not due to simple modification of the red pigment; for these colours, due to interference, fork over the area occupied by the red lines. The distinctions between these forms cannot therefore be simply chemical, as we may suppose them to be, for instance, in the case of many red and yellow forms, and the genetic relationships of the Heliconid varieties would raise many novel problems and be well worth studying experimentally.

[8] Woodeforde, F. C., Trans. North Staffordshire Field Club, XXXV, 1901, Plate.

[9] E. GallÉ, Compte Rendus du Congres Internat. de Bot. a l'Expos. Univ., 1900, p. 112.

[10] Flora of Mentone, 1864-8, Nova Acta Acad. Caes., XXXV, 1869.

[11] I owe these facts to Canon A. M. Norman, who showed me illustrative specimens. They were originally described by Bowerbank (Monogr. Brit. Spongiadae, vol. II, pp. 18 and XX; vol. III, Pls. I and III). A specimen of G. compressa measured 5 inches, with a greatest width of 3-1/4 in. G. ciliata was found measuring 3 in. long and 3/4 in. wide. These dimensions are many times those of normal specimens.

[12] Coutagne, G., Recherches sur le Polymorphisme des Mollusques de France, Annales Soc. d'Agric. Sci. et Industr. Lyon, 1895.

[13] As to the synonymy and references see Coutagne, p. 45.

[14] A. Lang, Die Bastarde von H. hortensis Muller H. nemoralis L. Jena, G. Fischer, 1908; with a fine coloured plate showing the varieties of the species and their hybrids.

[15] With this evidence compare that given by A. Delcourt in his valuable papers lately published relating to the variations of Notonecta. See especially Bull. Sci. Fr. Belg., 1909, XLIII, p. 443; and C. R. Soc. Biol., 1909, LXVI, p. 589.

[16] Allen, J. A., Bull. Amer. Mus. N. H., III, 1891, pp. 51-54.

[17] J. T. Gulick, Evolution, Racial and Habitudinal, Carnegie Institution, Publication No. 25, 1905.

[18] A. G. Mayer, Mem. Mus. Comp. Anat. Harvard, Vol. XXVI, 1902, p. 117. From the tables given I cannot ascertain the actual numbers from the two intermediate valleys, but they were considerable.

[19] To which I was very kindly guided by Mr. C. T. Trechmann.

[20] Standfuss, Handbuch d. palÄarkt Gross-schmet, 1896, p. 321.

[21] Ent. Rec., XVIII, No. 7, 1906.

[22] This evidence was largely collected by Mr. G. T. Porritt, who has given much attention to the subject.

[23] Such direct action has of course been proved to occur in the case of several dimorphic larvae (e. g., A. betularia, itself) and pupae.

[24] See Harris, Proc. Ent. Soc. London, 1904, p. lxxii, and 1905, p. lxiii; also Hamling, Trans. City of London Ent. Soc., 1905, p. 5.

[25] I am indebted to Mr. Outram Bangs of the Harvard Museum for calling my attention to this remarkable case.

[26] Auk, 1889, VI, p. 219.

[27] Ann. N. Y. Acad. Sci., 1878, I, p. 149.

[28] Ann. N. Y. Acad. Sci., 1878, I, p. 149.

[29] Ibid, 1912, pp. 523-8.

[1] J. A. Allen, The North American Species of the Genus Colaptes, Considered with Special Reference to the Relationships of C. auratus and C. cafer. Bull. Am. Mus. Nat. Hist., IV, 1892.

[2] For a case in which a red-headed female × a black-headed male gave a black-headed female and a red-headed male, see Avian Mag., N. S., IV, pp. 49 and 329

[3] The other variations of this bird are also interesting and important. The normal male has a red head and a red throat. The female has a red head and a white throat, but varieties of the female are known with a black head, thus again illustrating the change from black to red. It should be noted that this is not a mere retention of a juvenile character, but, as the birds mature, the red feathers come up, or as an exception, the black. There is also a western species, ruber, in which both sexes have a great extension of red, and are alike. The male of nuchalis intergrades with this type, but the female does not.

[4] Dr. W. Brewster, for example, has a remarkable specimen of the Teal (Nettion carolinense) with a white collar strongly developed at the front and sides of the neck, in a place where the normal has no such mark.

[5] This variety is spoken of as the Ringed Guillemot and is sometimes regarded as a distinct species to which the name ringvia was given by BrÜnnich. In support of this view Dr. William Brewster, to whom I am indebted for much assistance in regard to the variation of birds, called my attention to observations of his own and also of Maynard's, that the ringed birds were sometimes mated together, though in a small minority (see Brewster, Proc. Boston Soc. N. H., XXII, 1883, p. 410). It would however be possible to produce many instances of varieties mated together though surrounded by a typical population (e. g., two varying Blackbirds, Zoologist, p. 2765; two varying Nightjars, ibid., p. 5278). I am inclined to believe that in nature matings between brothers and sisters are frequent in many species of animals, and that the production of sporadically varying colonies is thus greatly assisted.

[6] The Sap-suckers feed on trees and somewhat resemble our Spotted Woodpeckers in general appearance. Colaptes feeds on the ground and corresponds perhaps rather with the European Green Woodpecker.

[7] For an introduction to this example I am indebted to Mr. W. D. Miller of the American Museum of Natural History. Some account of the facts is given by Baird, Brewer, and Ridgway (A Hist. of N. Amer. Birds. 1874, II, pp. 540, 544, etc.). S. varius occupies the whole country in suitable places from the Atlantic to the eastern slopes of the Rockies, and all Mexico to Guatemala. S. nuchalis was first known from the Southern Rockies only, but many were afterwards taken in Utah. S. ruber is restricted to the Pacific coast. In Ridgway's opinion all three are geographical forms of one species. In ruber the sexes are alike having both a great extension of the red in the throat, and a red crescent. The male of nuchalis grades to the ruber form, but the female does not. This female has some red in the throat like the male of varius, whereas the female of varius has a whitish throat.

[8] Not only vertebrates but the marine Crustacea and Mollusca illustrate this curious "principle" of variation, as Canon Norman formerly pointed out to me with abundant illustrations. There are of course cases to the contrary also.

[9] Chapman, F. M., Bull. Amer. Mus., IV, 1892, p. 1; see also Ridgway, Birds of North and Middle America, 1902, Part II, p. 214.

[10] It would aid greatly in factorial analysis if the descriptive term "green" could be avoided in application to cases where the green effect is due only to a mixture of black and yellow pigments. The absence of yellow is the sole difference between the mantle and underparts of pinus and chrysoptera.

[11] Bull. Amer. Mus. Nat. Hist., XXIII, 1907, p. 467.

[12] References on this subject will be found in Brit. Mus. Cat. Birds, XVII, p. 13.

[13] For these facts I am indebted to Mr. W. L. W. Field, who has lately published an account of his observations and experiments. See especially, Psyche, 1910, XVII, No. 3, where full references to previous publications are given.

[14] For the facts and further references see W. H. Edwards, Butterflies of N. America, 2d series, Papilio VII and X; 3d series, 1897, Papilio IV, Can. Entom., 1895, XXVII, p. 239.

[15] I think this case is fairly included because the machaon type is so widespread that it cannot be regarded as a product of a Northern climate, nor can asterias be claimed as especially a warm country form, seeing that brevicauda, which is scarcely distinguishable from asterias, inhabits Newfoundland (having a curious phase there in which the yellow is largely replaced by red).

[1] Often referred to by older writers as Meone, Esper's name.

[2] There are also two distinct island forms, unlike the European, Xiphia of Madeira, and a smaller variety, Xiphioides of Canary. See especially, Baker, G. T., Trans. Ent. Soc. London, 1891, p. 292.

[3] Speyer, Adolf, and August. Verbreitung der Schmetterlinge, 1858, I, p. 217.

[4] Lepid. ComparÉe, fsc. III, p. 372.

[5] Mr. Rowland-Brown has called my attention to a statement by Dr. Vaillantin (Petites Nouv. Ent., II, 235) that in Indre-et-Cher the first brood is of the northern type and the second of the southern. My experience is that in captivity these distinctions do not occur, and I have true egeria as first brood from Vienne and as the late brood from the Landes. I never collected in Indre-et-Cher.

[6] I have since seen true egeria from Ferrol in the extreme northwest, which was in Mr. Tutt's collection.

[7] Mr. G. Wheeler kindly showed me a series identical with this type, from Guernsey, and others from near Laon.

[8] Ent. Rec., V, 1894, p. 134.

[9] Mr. Wheeler has some pale but rather worn specimens from the Rhone Valley at Vernayaz.

[10] See Fleck, E., Die Macrolep. RumÄniens, Bul. Soc. Sciinte, VIII, 1899, p. 720.

[11] My experience agrees with that of Mr. H. Williams (Ent. Rec., VIII, 1896, p. 181) that pupae, well-formed, can stand considerable frost; but I used to find that half-grown larvae usually died if unprotected, and I believe that larvae which attempted to pupate in warm autumn weather and then got caught by frosts, always died. Small larvae which can creep into shelter at the bottom of the plants survived, and I expect that in the north the winter is usually passed in that state (see also Merrifield, F., Ent. Rec., VIII, 1896, p. 168, and Carpenter, J. H., ibid.).

[12] Some most unlikely species do this. I once had a larva of Parnassius delius, found at about 5,500 feet, which emerged late in the autumn (in October I believe), a season at which it must have perished in its own country.

[13] See, for examples, Barrett, G. C., Lepidoptera of the Brit. Islands, I, 1893, p. 229; also Grover, W., Ent. Rec., IX, 1897, p. 314; Williams, H., Proc. Ent. Soc., 1898, who reared several specimens from the New Forest which would pass for Bretons, though the rest of the family were true egerides.

[14] Above the Tosa falls.

[15] Bul. Soc. Sciinte, VIII, 1899, p. 691.

[16] The fact that Weismann by heating pupÆ obtained only one autumn specimen seems to me to show rather that a second brood can be produced than that it cannot, which is the inference usually drawn.

[17] Schima, K., Verh. Zool. bot. Ges. Wien, LX, 1910, p. 268.

[18] Rhopalocera Palaearctica, Florence, 1905-11, especially Pl. XXXII.

[19] See figures in Barrett, G. C., Lepidoptera of Brit. Islands, I, pt. 3, p. 25.

[20] Tutt, J. W., Ent. Rec., XVIII, 1905, p. 5. In the same place he states that on the Mendel Pass arcania "runs into" darwiniana and that in the Tyrolean localities the transition is especially evident. Wheeler (ibid., XIII, 1901, p. 121) expresses the contrary opinion, that satyrion does grade to arcania.

[21] H. Rowland-Brown, Ent. Rec., XI, 1899, p. 293.

[22] Speyer, Stettiner, Ent. Ztg., XXXI, 1870, p. 63.

[23] In regard to the closely analogous case of Spilosoma lubricipeda, Standfuss makes a similar statement. He bred the type on a large scale with the radiate form which he calls intermedia, and says that in four years of miscellaneous crossing he never obtained really transitional forms. Nevertheless after examining large series, especially those of Mr. W. H. B. Fletcher, I came to the conclusion that several might be so classed, but I am quite prepared to find that such specimens are heterozygous. (See Standfuss, Handb. d. Gross-Schmet., 1896, p. 307.) It is by no means unlikely that various dark forms of lubricipeda correspond with a progressive series of factorial additions. Many of the stages have been named, and of these the most definite are the intermedia of Standfuss (probably = eboraci of Tugwell) and the very dark Zatima of Heligoland, in which only the thorax, the nervures and a small field in the fore-wings remain yellow. A form was bred by Deschange from Zatima in which even the field in the forewing is obliterated. The exact circumstances in which Zatima occurs in Heligoland would be worthy of special investigation, for the normal lubricipeda is also found on the island. For references as to the British occurrences see especially, Hewett, W., Naturalist, 1894, p. 353. As to Zatima see especially Krancher, Soc. Ent., II, 1887-8, p. 26. I am indebted to Dr. Hartlaub for information as to the Heligoland types.

[24] Boisduval, Bull. Soc. Ent. Fr., III, 1834, p. 5.

[25] The systematics of Setina have been much controverted, but no one I believe doubts that aurita and ramosa are forms of one species. See also Chapman, A. T., Ent. Rec., XIII, 1901, p. 139.

[26] Arch. Naturg., 33, 1867, p. 116.

[27] Brit. Mus. Cat., Batrachia Gradientia, 1882.

[28] The Geographical Distribution of nearly related Species. Amer. Nat., XLI. 1907, p. 207.

[29] See later, p. 242.

[1] Semon, R., Der Stand der Frage nach der Vererbung erworbener Eigenschaften, published in Fortschr. der naturw. Forschung., Bd. 11, 1910.

[2] Standfuss, M., Denks. Schweiz. naturf. Ges., XXXVI, 1898, p. 32.

[3] Fischer, E., Allg. Ztschr. f. Entomologie, Bd. VI, 1901.

[4] Out of 12 pupae treated 8 died and of the 4 survivors, one only was affected. See M. v. Linden, Archiv. Rassen. u. Gesells., 1904, I.

[5] For illustrations see Oberthur's Études d'Entom., 1896, where many of these curious aberrations are represented; also Barrett, Lepid. Brit. Islands, II, pp. 71 and 72.

[6] SchÜbeler, F. C., Die Culturpflanzen Norwegens, 1862, especially pp. 24 and 28.

[7] I am obliged to him and to Dr. E. Gold for much trouble taken to answer my questions. Some idea of the kind of weather indicated by an average of 2.76° C. above the mean may be got from a comparison with the year 1911, which most people will remember as one of the hottest summers they have known. The July of that year was in east and southeast England about 4° F. above the mean but 2.67 C. means about 4.8° F. above the mean. At Greenwich July, 1859, was about 6.5° F. above the average.

[8] Wille, N., Biol. Cbltt., XXV, 1905, p. 521.

[9] Wettstein, R. von. Der Neo-marckismus u. seine Beziehungen zum Darwinismus, Jena, 1903.

[10] T. Graham Brown, Proc. Roy. Soc., 1912, vol. 84, B, p. 555. This paper gives full reference to the previous literature of the subject.

[11] Morgan, T. H., Evolution and Adaptation, New York, 1903.

[12] Kammerer's chief paper on this subject is in Arch. f. Entwm., 1909, XXVIII, p. 447, and it is to this that the paginal references in the present text relate. His previous paper appeared, ibid., 1906, XXII, p. 48. An account of his further experiments with Alytes is given in Natur, 1909-10, Heft 6, p. 95.

[13] In reply to my letter Dr. Kammerer who was then away from home very kindly replied that he was not quite sure whether he had killed specimens of Alytes with "Brunftschwielen" or whether he only had living males of the fourth generation, but that he would send illustrative material.

[14] Kammerer, P., Natur, 12 December, 1909, Heft 6, p. 95, repeated in 12 Flugschrift d. Deutsch Ges. f. ZÜchtungskunde, Berlin, 1910.

[15] Festschrift zum Andenken an Gregor Mendel, being vol. XLIX of the Verh. Naturf. Ver. in BrÜnn, 1911, p. 98.

[16] Kammerer's chief papers on this subject are Archiv fur Entwm., XVII, 1904, and ibid., XXV, 1907. An epitome of results is also given by him in 12 Flugschrift d. Deutsch. Ges. f. ZÜchtungskunde, Berlin, 1910.

[17] "Bei Fortdauer der Versuchsbedingungen sind als Vollmolche geborene Salamandra maculosa gleich bei der ersten Geburt abermals voll molchgebÄrend, benutzen zum Geburtsakt das trockene Land, und zwar unter Erreichung der (bei Salamandra atra normalen) Embryonen-Zweizahl," Kammerer, 1907, p. 49.

[18] 1904, p. 56.

[19] Throughout Kammerer's papers this is used almost as a technical term. It means, I presume, that the feature was manifested more than once.

[20] It should be stated that the papers contain a quantity of detail, especially descriptive of the state of the larvae, which I have not attempted to represent, but the account here given contains all that seemed essential to an understanding of the more important features of the account.

[21] The first appeared in Natur, 1909-10, Heft 6, p. 94; and the second, which contains coloured plates of the animals, in the lecture already referred to, 12 Flugschr. d. Deut. Ges. f. ZÜchtungkunde, Berlin, 1910, p. 26. In the paper in Mendel Festschrift, 1911, the subject is continued, but no more is added as to this part of the experiment.

[22] E. G. Boulenger, Proc. Zool. Soc., 1911, p. 323.

[23] Mendel Festschrift, 1911, p. 84.

[24] 12 Flugschrift. Deut. Ges. ZÜchtungskunde, 1910, Fig. 15, P. Reihe.

[25] Mendel Festschrift, 1911, p. 83.

[26] Field, 1912, 30 March.

[27] Ibid., 1904, p. 863.

[28] Mitth. Naturw. Ver. a. d. Univ. Wien, 1908, p. 53.

[29] As to the variations of Lacerta muralis in Western Europe and North Africa see Boulenger, G. A., Trans. Zool. Soc., 1905, vol. XVII, p. 351.

[30] As to the experiments of Klebs relating to the transmission of acquired characters, see Appendix.

[1] Pringsheim, H., Die VariabilitÄt niederer Organismen, Berlin, 1910.

[2] F. Wolf, Modifikationen u. Mutationen von Bakterien, Zts. F. indukt. Abstam. u. Vererbungslehre, II, 1909, p. 90.

[3] Winslow, C. E. A. and A. R.,Systematic Relationships of the Coccaceae. New York. 1909.

[4] C. C. Dobell, Jour. Genetics, 1912, II, p. 201, where full references are given.
Still more recently the same author has contributed an excellent summary of the evidence relating to bacteria (ibid., II. 1913, p. 325).

[5] See Woltereck, Verh. d. Deut. Zool. Ges., 1909, p. 110; and 1911, p. 142. This is a subject which can only be properly appreciated on reference to the original papers. Several complications are involved to which I have not here alluded.

[6] Proc. Roy. Soc., B, Vol. 86, 1913, p. 113.

[7] An Investigation of Evolution in Chrysomelid Beetles of the Genus Leptinotarsa, Carnegie Publications, 1906, No. 48.

[8] This is the famous Colorado beetle or potato-bug, which has caused such serious destruction in potato crops. There seems to be no doubt that this insect, formerly unknown in the eastern States, made its way east along the mining trails when the west was opened up.

[9] This is indicated in the coloured plate, but I have not found any explicit statement to this effect in the text, and am not sure if the absence of pigment was regarded as complete.

[10] Biol. Bull., XVIII, 1910, p. 285.

[11] This description does not quite agree with the representation of the larvae in Pl. 17 of the book Evolution in the Genus Leptinotarsa for there the larva of undecimlineata is shown as white in the second stage, but yellowish in the third stage; perhaps there is an error in printing.

[12] Biol. Bull., XX, 1910, p. 67.

[13] As to the interrelations of these three forms, Tower states (1906, p. 18) that angustovittata, which he reared from undecimlineata, is intermediate between it and signaticollis. Compare StÅl, "Monogr. des ChrysomÉlides," 1862, p. 163; and Jacoby, Biol. Centr. Amer. Celeopt., vi, Pt. 1, p. 234, Pl. xiii, fig. 20; Tab. 41, fig. 15; ibid., Suppl., p. 253. All these forms are evidently very closely related, and the delimitation of species is quite arbitrary. Jacoby indeed suggests that undecimlineata may be a variety of decemlineata.

[14] Gortner, Amer. Nat., Dec., 1911, XLV, p. 743.

[15] Mutations, Variations, and Relationships of the Oenotheras, Carnegie Institution Publication No. 81, 1907, pp. 61-64.

[16] Macdougal, D. T., "Alterations in Heredity induced by Ovarial Treatments", Bot. Gaz., vol. 51, 1911, p. 241.

[17] Payne, Fernandus, Biol. Bull., XVIII, 1910, p. 188, and ibid., XXI, 1911, p. 297.

[18] See especially, Mutation et Traumatismes, Paris, Felix Alcan, 1908.

[19] J. H. Powers, "Morphological Variation and its Causes in Amblystoma tigrinum." Studies from the Zoological Laboratory. The University of Nebraska, No. 71, 1907.

[20] In connexion with this case I would refer the reader to some remarkable observations of Dr. T. A. Chapman on various types of larvae which he reared from the moth Arctia caja (Ent. Rec., IV, 1893, p. 265, and following parts). From a single mother he raised a great diversity of forms, some which fed up rapidly and passed through their development without assuming certain stages, and others which were, as he called them, "laggards," moulting more times than their brethren and developing at a much slower rate. It is greatly to be hoped that such a case may be critically investigated by analytical breeding.

[1] Buffon, Hist. Nat., Oiseaux, 1780, VII, p. 3.

[2] Ibid., VIII, p. 115.

[3] Keeble, Jour. Gen., 1912, II, p. 173.

[4] Animals and Plants, ed. 1, 1868, II, pp. 180-5.

[5] Animals and Plants, ed. 1, 1868, II, p. 165.

[6] Species and Varieties, 1905, p. 471.

[7] Correns, Festschr. med.-nat. Ges. zur 84 Versamml. Deutsch. Naturf. u. Aertze. MÜnster i. W., 1912.

[8] This is a case of a somewhat different order and I mention it partly for that reason as an illustration of the complexity which such negative instances may present. The difficulty is that though the buffalo and the zebu can breed together, the foetus is too large to be born alive. (See Ackermann Ber. d. Ver. f. Naturk., Kassel, 1898, p. 69. Prof. S. Nathusius, of Halle, who has great experience in crossing Bovidae, tells me that he has always failed to cross the buffalo with other species.)

[9] In a paper to be published in the Report of the Genetic Conference, Paris, 1911, Bellair states that he obtained some partially fertile hybrids in the cross N. sylvestris × tabacum. As to the various degrees of sterility in hybrids between Nicotiana species see Lock, R. H., Ann. Roy. Bot. Gardens. Peradeniya, IV, 1909, p. 195.

[10] Beitrage zur Biol. der Pflanzen., X, 1911, p. 379.

[11] One very peculiar feature was observed, namely, that all the new forms in F₂ which were bred from came true. As I understand, this statement applied to five such new types, and they were represented by 76 individuals in F₃, but further details on this point are desirable. Another curious fact was observed, namely that one of the F₁ forms (cochleata × radiata) when fertilised by cochleata gave a highly polymorphic family, but fertilised by radiata the resulting offspring were almost uniform.

[12] I also had a few F₁ seeds given me by Mr. R. H. Lock.

[13] In a paper about to appear in Jour. Linn. Soc. Mr. A. W. Sutton identifies this Palestine pea as Pisum humile of Boissier and NoÉ.

[14] Lloyd, R. E., The Growth of Groups in the Animal Kingdom, London, 1912.