Besides reptiles, many other animals possess poison-glands and inoculatory organs which they employ, either to defend themselves against their natural enemies, or to capture the living prey upon which they feed.

The venoms that they produce are still, for the most part, but little understood. A few of them, however, have excited the curiosity of physiologists, especially those secreted by certain batrachians, such as the Toad, and certain fishes, such as the Weever. Some of them exhibit close affinity to snake-venom, and are composed, like the latter, of proteic substances modifiable by heat and precipitable by alcohol; others possess altogether special characters, and resemble alkaloids.

The lowest animal group in which these secretions begin to be clearly differentiated is that of the Coelenterates.

A.—Coelenterates.

It has been shown by Charles Richet108 that the tentacles of sea-anemones (Anemone scultata) contain a toxic substance which has the carious property of causing intense itching, pruritus, and even urticaria. This poison is perfectly soluble in alcohol, and can be prepared in the following manner:—

The tentacles are cut off close to the body of the animal, and immersed for a few days in an equal weight of alcohol at 95° C. The red liquid that results is decanted, and then filtered. The insoluble material is compressed, and yields large quantities of fluid, which is filtered and mixed with the previous liquid.

The whole is then evaporated in vacuo until there remains a thick oily liquid, which forms a red deposit. Filtration through paper is again employed, in order to separate this colouring matter, and to the filtered liquid is added an equal amount of alcohol at 95° C. By this means there is precipitated a blackish, gummy matter, insoluble in alcohol. The remaining liquid is decanted and once more evaporated until it is reduced to a smaller volume than before. It is again treated with twice its volume of absolute alcohol, when it precipitates, in addition to salts and gummy matter, a white flocculent substance, which is crude thalassin. This can be purified by redissolving it in alcohol at a temperature of 98° C. On cooling it separates from the fluid in the form of crystals, which are placed on a filter and can then be redissolved in a small quantity of water. Absolute alcohol, added to this solution, precipitates the thalassin in the shape of very pure crystals, which contain 10 per cent. of azote, and melt at 200° C.

This substance, in aqueous solutions, rapidly deteriorates owing to ammoniacal fermentation. When injected intravenously into dogs it produces pruritus, sneezing, and erythema, with intense congestion of the mucous membranes; 1 decigramme per kilogramme is a dose sufficient to produce these symptoms. It is not very toxic, since 1 centigramme is not lethal.

One kilogramme of anemones is capable of furnishing about 3 grammes of pure crystallised poison.

In addition to thalassin, Richet succeeded in isolating from the tentacles of the same sea-anemones another poison insoluble in alcohol at 50° C., and richer in azote (14 per cent.), to which he has given the name congestin. This is not destroyed by heating to 107° C. It is prepared by precipitating, by four times its volume of alcohol, a solution of anemone-tentacles in 5 per cent. fluoride of sodium. The solid matter, after being precipitated and dried, is redissolved in six times its volume of water, and then filtered. On adding to the filtered and fluorescent liquid its volume of alcohol at 90° C., the congestin is precipitated. It is purified by redissolving it in water, and freeing it by dialysis from the fluoride of sodium that it has retained. In this way there is obtained, after evaporation, a product sufficiently toxic to kill dogs in twenty-four hours in a dose of 2 milligrammes per kilogramme.

Congestin exerts a sensitising or anaphylactic effect upon animals as regards thalassin, and is lethal in a dose of about 5 milligrammes per kilogramme of animal, and sometimes even in a dose of 7 decimilligrammes. It is therefore a very active poison.

Dogs, on the other hand, into which is injected first thalassin, and then, some time afterwards, congestin, are perfectly resistant to inoculation by the latter. Thalassin is therefore antitoxic or antagonistic to congestin.

The latter, on the contrary, if injected first of all in non-lethal doses, renders animals so sensitive to inoculation with thalassin, that from 4 to 5 milligrammes are sufficient to cause death.

The tentacles of these anemones therefore contain two toxic substances antagonistic to each other, which can easily be separated, since one (thalassin) is soluble in concentrated alcohol, while the other is completely insoluble in this reagent.

These poisons are not only extremely interesting from a physiological point of view, but also possess a practical interest, since it is at the present time almost a matter of certainty that they are the cause of a malady which specially affects sponge-divers in the Mediterranean.

A good description of the disease has been given by Dr. SkÉvos Zervos, of Athens.109 It is observed exclusively in men who dive quite naked, without a diving-dress. Now, beside the bases of the sponges and sometimes on their surface there live numbers of anemones which secrete a viscid substance, which is extremely virulent, especially in the month of August.

The first symptoms that supervene after contact with these Coelenterates are an intense itching and burning sensation; a papule of a horny consistency appears at the outset at the spot at which contact took place; this is soon surrounded by a red zone, which becomes bluish and then black, and spreads to a greater or lesser extent, according to the region attacked and the virulence of the venom. After a few days the skin sloughs and leaves a deep ulcer, which suppurates in spite of antiseptic treatment. The onset of the disease is marked by a febrile attack with shivering, which is soon accompanied by cephalalgia, thirst, and pains in the back and limbs.

Zervos reproduced these disorders experimentally by rubbing an anemone, held with forceps, on the shaven abdomen of a dog. In a few minutes the region affected became quite red and pruriginous; twenty-five minutes later phlyctenÆ full of serum appeared; three days afterwards five abscesses of different sizes developed, while at the place where it had been touched by the venom the skin assumed a deep blue colour; on the fifth day an area 2 cm. in diameter was completely gangrenous.

When ingested, anemones possess toxic properties which are well known to the sponge-fishers, for they frequently make use of them for the purpose of poisoning domestic animals. With this object they cut them up into small fragments, and mix them with bread or meat, which is given to the animals to eat; the latter die in convulsions in a few minutes.

In order to preserve the divers from the harmful effects produced by contact with the anemones, they should be advised to cover their bodies with a layer of grease, a simple artifice which constitutes an efficient protection.

B.—Echinoderms.

The Echinoidea (Sea-urchins) are provided with soft prehensile organs, the pedicellariÆ, of which four kinds are distinguished: gemmiform, tridactyle, trifoliate, and ophiocephalous.

These pedicellariÆ contain a special venom, which causes the paralysis and death of animals into which it is injected. Uexkull, who was the first to mention it, considered that the gemmiform pedicellariÆ alone are toxic.

From this point of view various species of sea-urchins, Strongylocentrotus lividus, Arbacia Æquituberculata, SphÆrechinus granularis and Spatangus purpureus, have recently been studied by V. Henri and Mdlle. Kayalof.110

The pedicellariÆ were removed and pounded up in sea-water, and the pulp was injected into crabs, holothurians, star-fish, cuttle-fish, frogs, lizards, and rabbits; in the case of cuttle-fish and rabbits the injection was made intravenously; in that of the other animals into the body-cavity.

For crabs the lethal dose was from 20 to 30 gemmiform pedicellariÆ of Strongylocentrotus lividus.

The holothurians, star-fish, and frogs proved immune.

In the case of rabbits weighing 1½ kilogrammes, 40 pedicellariÆ of SphÆrechinus granularis, pounded up in 1 c.c. of water, produce death by asphyxia and general paralysis in from two to three minutes. The heart continues to beat after respiration has ceased.

For lizards and fishes the toxic dose is the same as for the crab. The cuttle-fish is paralysed and killed in two hours by 50 pedicellariÆ.

This venom resists ebullition for fifteen minutes.

V. Henri and Mdlle. Kayalof made experiments in immunisation. Rabbits that receive every third day increasing doses of gemmiform pedicellariÆ of SphÆrechinus granularis tolerate well, after four injections, the toxin of 40 pedicellariÆ, a lethal dose. The serum of these rabbits is not protective for either rabbit, crab, or fishes.

Frog serum (1 c.c.) injected into the body cavity of a crab, protects this animal against the pulp of pedicellariÆ injected immediately afterwards.

The pedicellariÆ easily become detached from sea-urchins. They remain fixed to objects which come into contact with them, and the urchin abandons them like poisoned arrows.

On touching a point on the surface of the body of an urchin, the spines are seen to incline towards the spot touched, and the pedicellariÆ stretch themselves out and lean with their valves open towards the seat of the stimulus. In SphÆrechinus granularis the heads of the gemmiform pedicellariÆ are covered with sticky mucus forming a tiny drop, visible under the lens. A specimen of this species possesses more than 450 pedicellariÆ.

C.—Arthropods.

(a) Araneida (Spiders).

Almost all Arachnids possess poison-glands, which are connected, in some cases with the buccal apparatus, in others with a special inoculatory organ situated at the posterior extremity of the body. The spiders and scorpions belong to this group, and their venom is particularly active.

On each side of the mouth of spiders is found an appendage ending in a fang (chelicera), at the extremity of which opens the excretory duct of a more or less developed poison-gland. The venom produced by these glands is instantly fatal to all small animals upon which spiders feed. In man and large mammals their bite produces sensations of pain accompanied by swelling and muscular contractions as though caused by localised tetanus.

The venom of certain species of spiders sometimes causes very serious and even fatal results. Latrodectus malmignattus (the malmignatte of the South of France and Italy), and especially Latrodectus mactans, of Chile (fig. 96), are greatly dreaded.111 The area of distribution of the latter includes the whole of Tropical and Sub-tropical America. It is said that it frequently causes the death of milch cows, and that in man its bite produces tetanic effects, which last for several days, but are in most cases amenable to treatment.

Another dangerous spider is the Katipo (Latrodectus scelio), of New Zealand. This creature is confined to the sea-shore, and the natives are often bitten when collecting shell-fish or sea-weed. The Maoris are so much afraid of the bite of the Katipo that, when one of them has been bitten in his hut, and the animal cannot be found, they do not hesitate to burn the dwelling to the ground. Moreover, they are convinced that the death of the spider is absolutely necessary for the recovery of the patient.112

Kobert113 has made an experimental study of the venom of species of Latrodectus and Epeira. That of Latrodectus erebus (the Karakurte of South Russia) is particularly toxic.

If a dry extract of these spiders be prepared and injected into the veins of dogs or cats, it is found that a few milligrammes per kilogramme are sufficient to cause death, with phenomena of dyspnoea, convulsions, and progressive paralysis of respiration and the heart. Rabbits, rats, birds, frogs, and leeches are also sensitive to this poison, though the hedgehog is almost refractory. The young spiders, and even the eggs, are more toxic than the adults.

Spider-venom is destroyed by heating for forty minutes at + 70° C., and is precipitated by alcohol. When absorbed by ingestion it has no effect: it is hÆmolytic and coagulates blood.

The study of arachnolysin by Ehrlich’s methods has been undertaken afresh by Hans Sachs,114 who has shown that rat’s and rabbit’s blood are most rapidly dissolved. Twenty-eight milligrammes of extract of Epeira are capable of completely dissolving 0·05 c.c. of blood.

By immunising guinea-pigs and rabbits, Sachs succeeded in obtaining a strongly antitoxic serum, which entirely prevents the hÆmolysis of the sensitive red corpuscles.

(b) Scorpionidea (Scorpions).

The poison-apparatus of the scorpion is constituted by the last abdominal segment (telson), which is swollen and globular, and terminated by a hard, curved spine, with a very sharp point, near which can be distinguished, under the lens, two small oval orifices by which the poison is enabled to escape (fig. 97).

The poison-glands are two in number, symmetrically placed in cavities, each of which is completely filled by the gland. They are separated from each other by a muscular septum formed of striated fibres inserted in the chitinous skeleton; by the contraction of this septum the animal is enabled to eject its venom.

The scorpion never stings backwards, but always in front of itself. It delivers stabs with its sting in two distinct ways. For the purpose of defending itself from attack it elevates its abdomen into a bow, and then regains its former position by suddenly unbending it. To strike an animal, such as a spider, which serves it for food, the scorpion seizes it with its pincers and holds it as in a vice. Then it raises its abdomen, brings the end of it close to its captive, and, with a lever-like movement, drives the sting into its body. The victim immediately becomes paralysed and motionless.115

The poison-glands of a Scorpio occitanus from the South of France contain about 1 to 10 centigrammes of a toxic liquid, capable of furnishing 10 to 15 per cent. of dry extract. This liquid is decidedly acid; it reddens litmus paper and is miscible with water.

Its physiological effects are especially intense in the case of the arthropods upon which the scorpion habitually feeds, and in that of vertebrates in general. Batrachians, fishes, birds, and mammals are extremely susceptible to this poison. Half a milligramme of dry extract injected subcutaneously is sufficient to kill a guinea-pig, and 1 milligramme is lethal to the rabbit.

In poisoned animals there is first observed a period of violent excitement, accompanied by very acute pains; these are followed by muscular contractions, and finally by paralysis of the respiratory muscles, as in the case of intoxication by cobra-venom.

The effects of scorpion-poison, which clearly indicate the presence of a neurotoxin, have been very well described by Valentin,116 Paul Bert117 and Joyeux-Laffuie. Kyes118 has prepared a lecithide from scorpion-venom, which hÆmolyses red corpuscles as do the lecithides of cobra-venom, and I myself119 have established the fact that the antivenomous serum of a horse vaccinated against cobra-venom effectively protects mice and guinea-pigs against intoxication by the venom of Scorpio occitanus; this has been verified by Metchnikoff. There is, therefore, a close affinity between this venom and that of Colubrine snakes.

On the other hand, it has been shown by the investigations of C. Nicolle and G. Catouillard that the same antivenomous serum has no effect upon the much weaker venom of the scorpion of Tunis (Heterometrus maurus), which, in the case of man and mammals in general, scarcely does more than produce a transient oedema at the point of inoculation.

The venom of Heterometrus maurus is, however, toxic enough to the sparrow. When one of these little birds is inoculated in the pectoral muscles with the contents of the poison-glands of a single scorpion belonging to this species, the following symptoms are observed: Immediate rigidity, doubtless connected with the pain, then, after a few seconds, depression and relaxation of the muscles. The bird remains upright, but its body sinks down more and more until it comes into contact with the ground; if on a perch, it soon becomes unsteady and drops off. There is dyspnoea, which any effort increases, and death supervenes suddenly; all at once the sparrow falls on its side, stiffens, sometimes has a few convulsions, and then finally becomes still. The time occupied by these phenomena is always short, although it varies from two minutes to half an hour.

Scorpion-venom is a strong irritant to the mucous membranes. When dropped into the eye of a rabbit it produces acute ophthalmia.

It has often been asserted that scorpions kill themselves with their own venom if enclosed in a circle of fire. This is an absolute myth, for it is easy to prove by experiment, as was done by Bourne at Madras,120 that these animals cannot be intoxicated by their own poisonous secretion, nor by that of other individuals of the same species. Moreover, it has been established by Metchnikoff,121 in very definite fashion, that the blood of the scorpion is antitoxic. If 0·1 c.c. of this blood be added to a dose of venom lethal to mice in half an hour, a mouse injected with this mixture resists indefinitely. This antitoxic power is exhibited both by Scorpio afer and the Algerian Androctonus.

(c) Myriopods.

It has been shown by Phisalix and Bertrand that certain species of Myriopods, including those of the genus Julus (Order Chilognatha, e.g., Julus terrestris), secrete throughout the entire extent of their body a volatile venom, which these authors compared to quinone.

The species of the genus Scolopendra (Order Chilopoda; Scolopendra cingulata, found in the South of France, Spain and Italy; S. gigantea and other forms, common in Africa, India, Indo-China and Equatorial America), have the second pair of post maxillary appendages transformed into formidable poison-claws, with which they can inflict bites which are very painful to human beings.

The tropical species may attain a length of 10 or even 15 cm. Their bodies are composed of 21 segments, each provided with a pair of jointed legs. They live in shady places, such as woods, hidden under stones, dead leaves, or the bark of old trees. They feed upon small insects, spiders, and larvÆ, which they kill with their venom. The latter is secreted by a racemose gland situated at the base of the poison-claws; it escapes by a duct which opens at the apex.

This venom, the physiological study of which was commenced by Dubosq, is an acid, opalescent liquid, hardly miscible with water.

More complete experiments on this subject have been made by A. Briot,122 who prepared a solution by sectioning the labium and poison-claws, and crushing the whole in physiological salt solution. When injected intravenously into rabbits, it produces immediate paralysis, with coagulation of the blood; subcutaneously it leads to the formation of enormous abscesses, with necrosis of the tissues. Small animals, such as spiders, species of Scutigera, beetles, &c., are very sensitive to it.

The bite of ScolopendridÆ is very painful to human beings. In the Tropics such bites often cause somewhat serious results: insomnia, accelerated and intermittent pulse, and local oedema, which usually disappears after twenty-four hours. Well-authenticated fatal accidents have never been recorded (Bachelier,123 Saulie124).

(d) Insects.

A very large number of insects produce acrid or irritant secretions, which serve them as a means of defence, but cannot be considered as true venoms; the species of MeloË (oil-beetles) and Cantharis (blister-beetles), are the most remarkable in this respect.

The Order Hymenoptera is the only one that includes a multitude of species really provided with poison-glands and an inoculatory apparatus.

The poison-organs, which have been well studied, especially by Leuckart,125 Leydig,126 Carlet,127 and more especially by L. Bordas,128 Janet,129 and Seurat,130 always include two and sometimes three kinds of glands: the acid gland, the alkaline gland or gland of Dufour, and the accessory poison-gland (fig. 99).

The acid gland comprises a glandular portion (which sometimes takes the shape of a long flexuous tube, always bifid at its extremity, sometimes that of two tubes, simple or ramified, or again is composed of a bundle of cylindrical, simple or multifid canals), a poison-sac or reservoir, ovoid or spherical in shape, and an excretory duct, which is usually short.

The alkaline gland, or gland of Dufour, exists in all Hymenoptera, and presents the appearance of an irregular tube, with a striated surface and a spherical or conical upper extremity. Its excretory duct opens, beside that of the acid gland, at the enlarged base of the gorget of the sting (fig. 100).

The accessory poison-gland, which is lanceolate or ovoid in shape, consists of a small, granular mass, the extremely narrow excretory duct of which opens at almost the same point as that of the alkaline gland. It does not exist in all Hymenoptera.

The stings of hive bees (Apis mellifica), wasps (Vespa vulgaris), violet carpenter bees (Xylocopa violacea), and humble bees (Bombus lapidarius) cause considerable discomfort. The venom of the carpenter bee, which is of some strength, has been studied by P. Bert, and I have myself made experiments with that of the hive bee (A. mellifica). The venom extracted from a couple of bees, by crushing the posterior extremity of the body in 1 c.c. of water, is sufficient to kill a mouse or a sparrow.

Death supervenes in a few minutes, from respiratory asphyxia, as in the case of intoxication by the venom of Colubrine snakes (Cobra). In the blood-vessels and in the heart the blood is black and remains fluid. It therefore appears that this venom contains a very active neurotoxin.

The phenomena of intoxication caused by the venom of these insects are, as a rule, slight, being limited to an acute pain, accompanied by a zone of oedema and burning itching. Sometimes however, when the stings are in the eyelids, lips, or tongue, they produce alarming and even fatal results, as shown by the following incident:—

On September 26, 1890, a young girl of Ville-d’Avray was eating grapes in the woods of Fausse-Repose, when she inadvertently swallowed a wasp. The unfortunate girl was stung in the back of the throat, and the wound became so rapidly inflamed that, in spite of the attentions of a doctor, she died in an hour from suffocation, in the arms of her friends.

Phisalix131 has studied the physiological action of bee-venom on sparrows inoculated either by the sting of the insect, or with an aqueous solution obtained by crushing the glands. In both cases a local effect, paralysis of the part inoculated, is first produced; this is followed by convulsions, which may last for several hours; the final stage is marked by coma and respiratory trouble, which ends in death.

After being heated for fifteen minutes at 100° C. the venom has no further local action; the general phenomena are merely diminished. If heated at 100° C. for thirty minutes, the venom ceases to cause convulsions, but remains stupefactive. Exposure for fifteen minutes to a temperature of 150° C. renders it completely inert.

This venom therefore comprises: (1) A phlogogenic substance, destroyed by ebullition, contained in the acid gland of the bee; (2) a poison causing convulsions, which does not resist a temperature of 100° C., if prolonged, and is probably produced by the alkaline gland; (3) a stupefactive poison, which is secreted by the acid gland, and is not entirely destroyed until a temperature of 150° C. is reached.

The poison-glands can easily be extracted by gently pulling at the stings of bees anÆsthetised by chloroform.

The eggs of bees, like those of the toad and the viper, contain the specific venom. The amount, however, is small, since in order to produce lethal results in the sparrow it was found necessary to inoculate an emulsion obtained by crushing 926 eggs.

Phisalix132 makes the approximate calculation that, in the egg the weight of the toxic substances amounts to the one hundred and fiftieth part of the whole. Their effects are similar to those produced by the venom itself, but the convulsions are not so severe. The predominant poison in the egg appears to be that causing paralysis.

I have easily succeeded in vaccinating mice against doses of bee-venom certainly lethal, by repeatedly inoculating them with very small doses. Moreover, we find the same thing in the case of human beings, for we know that those who are in the habit of handling hives become quite accustomed to bee-stings, and finally feel not the slightest effect from them.

It has been shown by J. Morgenroth and U. Carpi,133 in a paper recently published, that the venom of bees, like that of the scorpion, possesses the property of hÆmolysing the red corpuscles of several species of animals (the rabbit, guinea-pig, and goat), and that it is capable of combining with the lecithin to form a lecithide analogous to cobra-lecithide, the curious properties of which we have studied in detail.

This lecithide of bee-venom is from 200 to 500 times more hÆmolysing than the venom itself, and resists ebullition like that of the cobra. In order to isolate it Morgenroth and Carpi employed the method recommended by P. Kyes: 1½ c.c. of a solution of pure venom is mixed with 1½ c.c. of a 5 per cent. solution of lecithin in methylic alcohol. After being kept for twenty-four hours at 37° C., 22 c.c. of absolute alcohol are added; the liquid is decanted, and the clear filtrate is mixed with 150 c.c. of ether. There is slowly formed a somewhat copious flocculent deposit, which is collected on a filter, washed several times with ether, and finally dried. The lecithide that remains on the filter dissolves completely in physiological salt solution.

It must be remarked that bee-venom, without the addition of lecithin, gives a scanty precipitate with ether. This precipitate, dissolved in physiological salt solution, possesses no hÆmolysing power. The lecithide, on the contrary, dissolves red corpuscles almost instantaneously.

Normal horse-serum considerably inhibits hÆmolysis by bee-venom + lecithin. This protective action of normal serums has already been observed by Langer; it is perhaps attributable to the cholesterin that they contain.

Among other Hymenoptera capable of inflicting very severe stings may be mentioned the species of Polistes and certain Pompilids, especially a species of Pompilus found in Natal, the painful stings of which have sometimes been experienced and described by travellers (P. Fabre, of Commentry).134

In the family CrabronidÆ the females are provided with a sting and venom, which usually has little effect upon man, but is toxic to other insects. Thus, Cerceris bupresticida is remarkable for the stupefying effect of its venom upon the BuprestidÆ destined for the food of its larvÆ. It stings the beetles between the first and second segments of the thorax, with the result that the victim is paralysed, though in other respects its bodily functions appear to continue; in fact, its intestine is seen to empty itself at long intervals. These effects are attributed by Mons. J. H. Fabre, of Avignon, to the direct action of the venom upon the ganglia of the thoracic nervous system.

Instances of Hymenoptera belonging to the tribe Entomophaga actually depositing their eggs beneath the skin of man are mentioned by RaphaËl Blanchard.135

According to P. Fabre, the best treatment for wasp- or bee-stings would appear to consist in the application of strong saline solution, or a liniment of ammonia and olive oil. For my own part, I have tried hypochlorite of lime, in a 1 in 60 solution, or eau de Javel diluted to 1 per cent., and have always obtained such excellent results from these remedies that I do not hesitate to advise their use.

D.—Molluscs.

Certain Gastropodous Molluscs, chiefly Murex brandaris and M. trunculus, possess purple glands from which it is possible to extract a very active venom (RaphaËl Dubois)136 by crushing them up with sand and alcohol. The alcoholic liquid, filtered and evaporated in a water-bath, yields a brown oily fluid. The subcutaneous injection of a few drops of this into a frog is sufficient to produce very decided toxic effects. Sluggishness and slowness of movement are seen to supervene fairly quickly; reflex actions are still exhibited, but the animal is no longer able to jump.

If the dose be not too strong, this condition of paresis lasts for several hours, and then disappears. In most cases, however, the paresis is succeeded by complete paralysis, and the animal appears as though suffering from curare. Yet the fact is that the venom is neither curare-like nor cardiac; the heart, muscles, motor endplates, and motor and sensory nerves are spared; the nervous centres alone are attacked, especially the encephalon. The animal dies without convulsions.

Sea and fresh-water fishes (golden carp) are very sensitive to this venom; warm-blooded animals are refractory. It is therefore probable that, in the species of Murex, the purple gland is a poison-gland serving for defence, or for the capture of the prey upon which these molluscs feed.

Among the Cephalopods, the Octopods (Octopus vulgaris, common octopus, Eledone moschata, musky octopus, of the Mediterranean) possess two pairs of salivary glands, a small anterior pair, and a posterior pair of considerable size.

The Decapods (cuttle-fishes [Sepia], &c.), have only posterior salivary glands, of smaller dimensions in proportion to the size of the body.

On being crushed and macerated in water, the anterior glands yield a limpid and slightly acid juice; the posterior glands produce a viscid, ropy fluid, filterable with difficulty and neutral. The latter has an immediate paralysing effect upon Crustacea. It contains a substance of a diastasic nature, precipitable by alcohol, and destructible by heating for an hour at 58° C.

Owing to the poisonous properties of this juice, Octopods succeed in overpowering large prey, such as lobsters and crabs. Once they are seized by the tentacles of the octopus, or cuttle-fish, a bite inoculates these animals with venom that immediately destroys their power of movement, and the Cephalopod is able to continue its meal in perfect security, without having to fear the pincers of its prey.

An experimental study of this venom has been made by A. Briot,137 who found that crabs are very sensitive to it, while rats, frogs, rabbits, and fish do not appear to experience any inconvenience.