Elie Metchnikoff was now thirty years old, and his personality was fully characterised though it had not yet reached the culminating point of its development.

His dominating point was his passionate vocation; his worship of Science and of Reason made of him an inspired apostle. He had the faults and qualities of a rich and powerful nature. Vibrating through all the fibres of his being, he shed life and light around him. His temper was violent and passionate; he could bear no attack on the ideas which were dear to him, and became combative as soon as he thought them threatened. His was a wrestler’s temperament; obstacles exasperated his energy and he went straight for them, pursuing his object with an invincible tenacity; he never gave up a problem, however difficult, and never hesitated to face any sacrifice or any privation if he thought them necessary.

A strange contradiction with this iron will was offered by occasional disconcerting impulses, like that which caused the failure of his first journey abroad, or by sudden attacks of fury for insignificant reasons such as an unexpected noise in the street, a cat mewing or a dog barking, or angry impatience when he could not solve a frivolous puzzle, etc. This impulsive disposition gradually calmed down as he grew older, and ultimately very nearly disappeared.

In his personal relations also he was apt to lose his temper, but a reaction very soon followed the outburst, and his efforts to be forgiven when he felt guilty were very touching. On the other hand, he did not easily forget an offence, though no desire for revenge ever soiled his soul, and his gratitude for kindness was absolutely indestructible.

He harboured pessimistic theories to that extent that he looked upon the procreation of other lives as a crime on the part of a conscious being; his physical and moral sensitiveness was intense. And yet he had inherited from his mother a natural gaiety and delightful elasticity which always ended by gaining the upper hand. He was fond of joking; his wit was occasionally somewhat cutting, but that was entirely due to the appropriateness of his remarks; he never hurt people’s feelings intentionally. He sometimes gave offence by a professional habit of using personal and concrete instances by way of arguments, but he applied the process to himself as well; it was the objective method, nothing more, and those who knew him well never doubted it.

His benevolence was most active and never insipid, though marked by an almost feminine sensibility. He was an incomparable companion and friend, and had the gift of smoothing difficulties and inspiring courage, security, and confidence. He took the greatest interest in others and easily came down to their level, always finding points in common, “an opportunity for the study of human documents,” he said. Thus he conversed simply and sympathetically with the humble as with the great, with the young as with the old. It was no mere intellectual interest that he bore them, but he put his whole heart into it, which made him extremely easy to approach. And yet he never departed from absolute freedom of speech, sometimes mixed with harshness. Truth and sincerity, for him, came above everything; he carried the courage of his opinions to the highest degree, even if it was likely to shock his hearers or to do him harm. He jealously guarded his independence and nothing could force him to act against his convictions. Full of enthusiasm, always interesting, he enlivened all around him. His ideas and his activity were in constant effervescence; no serious question left him indifferent; he read everything, knew about almost everything, and willingly informed others; his vibrating expansiveness made him a centre of attraction in his private life as in the laboratory or in any other sphere of activity.

From 1873 to 1882 his energies were chiefly absorbed by teaching and by the inner life of the University of Odessa, into which he threw himself with his usual enthusiasm. His lectures were full of life, always bringing out general ideas to throw light upon the most arid facts; he made use of these as an architect utilises coarse materials in order to erect a harmonious edifice. His creative power endowed his lectures with an Æsthetic character in spite of their extreme simplicity; not that he concerned himself much about form, but because of his wealth of ideas and the logical way in which he developed them, starting from the simple and reaching the complex in a harmonious synthesis. His own enthusiasm established a living bond between him and his audience.

He was on excellent terms with the students, though he made no bid for popularity. Not only did he give no encouragement to the prevailing tendency of the young men towards politics, but he endeavoured on the contrary to bring them back to their studies; he tried to prove to them that social problems demand knowledge and a serious practical preparation. Otherwise, said he, social life would be as medicine was before it entered into the path of science, and when any middle-aged woman, any bone-setter, was allowed to practise therapeutics. At the same time, students found in him willing protection in the persecutions directed against them, and earnest help in their work when they showed the least interest in it; he would eagerly welcome the smallest spark of the “sacred fire.”

Owing to the absolute independence of his ideas and conduct he had great influence on young men, and this caused him to be looked upon in administrative spheres as a “Red”—almost an agitator. In reality he was struggling against the inertia and reactionary forces which were shackling the normal development of culture and science in Russia. He called himself a “progressive evolutionist,” for he considered that alone a deep and conscious evolution could give stable results and lead to real progress. He thought that Revolution, and especially Terrorism, merely provoked a reaction which might be long-lived, and that, as long as the people were not sufficiently educated, a revolution might easily result in the transfer of despotism from one party to another. Socialistic doctrines did not satisfy him; according to him, they did not leave sufficient scope to personal initiative and to the development of individuality, two factors which he considered as essential to every progress.

He looked upon scientific work as his mission, and avoided politics because he did not think himself competent to deal with them. But scientific activity being closely limited by the state of the University, which was badly oppressed at that time by reactionary powers, he was led to take part in the defence of the University’s right to autonomy. He brought all his energies into the struggle, though trying to keep from party tactics and to act purely in the interests of science. For instance, he would vote either for a Radical or a Conservative without sharing the opinions of either, but merely guided by their scientific value.

At the beginning of his scientific career at Odessa he led a very active campaign in favour of the teaching of Natural Science. He urged that, in order to teach properly, Natural History professors should themselves have made independent researches on living fauna and flora, and tried to introduce a series of measures to allow biologists special holidays and missions to desirable places, at the proper seasons, for research purposes. “There is no doubt,” he said, “that scientific activity would be much increased if the proposed measures were adopted. Then, before long, our young scientists would not need to go to study in German universities, but could go abroad already prepared to undertake independent research.” The Commission which examined his report demanded certain modifications, “because of the Imperial injunction to be very strict in granting travelling permits to professors.” Metchnikoff somewhat altered the text, which, after being adopted by the University Council, was rejected by the Ministry and remained without effect. Thus was every independent suggestion stifled, even when it had but a purely scientific object.

Soon the situation of the Odessa University became even more difficult. Between 1875 and 1880 reaction increased considerably, and the inner life of the University became very unfavourable to any scientific activity. Already before that it was teeming with intrigues, the Professors of Ukrainian origin being hostile to the “Muscovites.” Yet it was still possible to remain apart from these local intrigues, until political reaction, filtering into the University, created in it the deepest divisions. The hostility of parties was now based on political opinions, either “Reactionary” or “Liberal.” The students were being more and more carried away by this movement and no longer took any interest in their studies.

All these conditions made normal teaching and scientific work impossible, and Metchnikoff, seeing that politics from above and from below now swallowed up everything, tried to take refuge in his laboratory but in vain; even there he could no longer find the necessary calm, and only during the holidays could he really work.

Thus passed the years until March 1, 1881, when the crime which ended the days of Alexander II. was followed by a great reactionary movement. The authorities, seeing conspiracies and plots everywhere, persecuted without cause all the elements which were ticketed as “dangerous.” Though the University still preserved its autonomy, this was entirely fictitious, for the Ministry thwarted every desire for independence; the nomination of professors elected by the University Council was only ratified by the Ministry if they were reactionaries, without any regard for their scientific value. Soon the Chairs were occupied by ignorant men of doubtful morality.

The life and honour of the University became endangered, and Metchnikoff found himself obliged to take part in the struggle; he did so with vehemence and energy; the independence of the University was involved, and, as long as he could hope to save it, he struggled. At the meetings of the Council and of the Faculty he never failed to give vent to his critical opinions with a vehement frankness which earned him in the University the reputation of an “enfant terrible.” In the meanwhile every resolution passed by the Council, if not reactionary in character, was systematically quashed by the Ministry, which thus paralysed every means of action, and Metchnikoff found himself faced with the alternative of submitting or handing in his resignation. He decided for the latter: his convictions were involved, and moreover his health could not withstand the continual agitation and strain on his nerves.

As we could not afford to live in independence, he applied for a vacant post of entomologist in the zemstvo[13] of Poltava, and at the same time wrote out his resignation, holding it in readiness for an opportunity which was not long in coming.

The Conservative party in the Faculty arose against a Liberal professor who had accepted a very clever thesis in which the Reactionaries perceived Socialist tendencies. The Dean of the Faculty proposed that all such theses should be refused, and the Faculty approved. This was the signal for a storm in the University, the Dean was hooted by the students, and many of them were threatened with being expelled. The Curator desired the more influential professors, of whom Metchnikoff was one, to intervene with the students in order to bring disorder to an end, and the professors consented, on condition that the offending Dean should resign. The Curator promised that he should be asked to do so, and order was immediately restored; but the Dean remained and many students were severely and unjustly punished. Metchnikoff thereupon produced his resignation, which was promptly accepted, and thus his University career came to an end.

Besides his University lectures, he gave public lectures on Natural History which were attended by a number of female students, for women at that time were only admitted to the Faculty of Medicine, and these lectures were extremely useful to them. Metchnikoff, though he did not believe that women could accomplish creative work in science, was strongly in favour of higher education for women, considering it as necessary to their general intellectual development. Genius, he thought, was peculiar to the male sex, no woman having created anything “of genius” even in domains which had always been accessible to them, such as music, literature, and the applied arts. The very rare exceptions, to his mind, only proved the rule; yet he did not draw the conclusion that woman was in any sense inferior to man. He merely held that her gifts are different from those of men.

Metchnikoff’s health had been seriously shaken by the emotions and annoyances of university life. Already in 1877, after political intrigues at the University, he had felt the first symptoms of cardiac trouble, which were the beginning of a long period of ill-health. He consulted Bamberger, a great Viennese physician, who, however, found nothing serious, and merely forbade him the use of wine and tobacco, to neither of which was he addicted.

His health suffered further through the violent anxiety which he went through in 1880 whilst I lay dangerously ill with typhoid fever, contracted in Naples. Though worn out with devoted nursing, he tried to make up the time lost to research and over-worked himself, with the result that cardiac trouble was followed by fits of giddiness and unconquerable insomnia. He fell into such a state of neurasthenia that, in 1881, he resolved in a moment of depression to do away with his life.

In order to spare his family the sorrow of an obvious suicide, he inoculated himself with relapsing fever, choosing this disease in order to ascertain at the same time whether it could be inoculated through the blood. The answer was in the affirmative: he became very seriously ill. His condition was aggravated by anxiety concerning the University; for he was sufficiently conscious to be aware of the events which were taking place in Russia. The murder of Alexander II. caused him to foresee a political reaction of the most terrible type; already, a reactionary Rector had been appointed. Metchnikoff developed intense jaundice and had a serious relapse with alarming cardiac weakness; during the crisis he had a very distinct prevision of approaching death. This semi-conscious state was accompanied by a feeling of great happiness; he imagined that he had solved all human ethical questions. Much later, this fact led him to suppose that death could actually be attended by agreeable sensations.

His robust nature, however, triumphed over all these grave complications, and, during his convalescence, he was filled with a joy of living such as he had never experienced before; from that moment his moral and physical balance was completely restored. There was one unpleasant sequel to his illness, an acute affection of the sight (choroiditis), but it fortunately disappeared without leaving any traces, and, in fact, he never suffered again from his eyes, in spite of his constant use of the microscope.

After his recovery he had a renascence of vital intensity; the life instinct developed in him in a high degree; his health became flourishing, his energy and power for work greater than ever, and the pessimism of his youth began to pale before the optimistic dawn of his maturity. However, the relapsing fever had very probably increased, if not started, the cardiac trouble which eventually caused his death.

During the time when Metchnikoff was forbidden the use of the microscope on account of his eye weakness, he studied EphemeridÆ from the point of view of natural selection. He wished to elucidate the manner in which this selection operates during the very short life of those insects: the rudimentary structure of their buccal organs does not allow them to feed themselves, and they have no time to adapt themselves to external conditions.

During the 1875 holidays, at Gmunden and on the Danube, he observed the nuptial flight of the mayflies, a phenomenon which constitutes their short adult existence, preceded by a long period in the larval state. Thousands of these diaphanous, ephemeral insects swarm above the water in a compact cloud; now and then, dead EphemeridÆ fall like snow-flakes, and that is the final and tragic completion of the nuptial flight. Metchnikoff wished to unveil the mechanism of this sudden death, evidently due to a physiological cause; but he obtained no definite results either that year or the following, when he continued his observations in the Caucasus. He realised that the life of these insects was too short to allow him to solve the problems which interested him, and, his eyes now being cured, he went back to his studies on the origin of multicellular beings or metazoa.

He studied the development of inferior sponges and ascertained that they possess the three embryonic layers which correspond to those of other animal types, but that these layers have not the same degree of independence or differentiation. He found that in certain inferior sponges the mesoderm develops before the endoderm and gives birth to it. These two layers, born one from the other, manifest common primordial characters. Therefore he was in no wise surprised to discover that, in these inferior sponges, the amoeboid and mobile cells of the mesoderm fulfil digestive functions equally with, and even more than those of the endoderm; in fact, with primitive beings, functional characters are not more strictly delimitated than morphological characters. It is only a more advanced differentiation which separates them.

He connected these new facts with that which he had observed in 1865 in one of the lower worms, the earth planarian Geodesmus bilineatus. This worm is actually without a digestive cavity, for the latter is entirely filled by parenchymatous cells inside which digestion takes place.

By their primitive structure, lower sponges and worms come near the higher Infusoria, to which they are even more closely related by this intercellular digestion which is common to them.

This led Metchnikoff to ask himself whether this was not, generally speaking, the primitive mode of digestion. He carried out numerous researches on this point during the following years, and found the same intercellular digestion in other lower worms, such as the Mesostoma and aquatic planarians, and afterwards in some lower Coelentera and some Echinoderma. He was thus enabled to establish definitely that the primitive mode of digestion was really intercellular, for the lower multicellular animals either do not possess any digestive cavity or else their digestive cavity develops late, as for instance with lower jelly-fish or with hydropolypi. Even when the cavity is developed in these inferior animals, the digestive functions are fulfilled by the mesodermic cells.

The question as to what are the ancestral forms of multicellular animals cannot be solved through direct observation, for there is a lacuna between them and unicellular beings, a lacuna which is due to the disappearance of intermediary forms. It can only be filled by hypotheses, based upon the embryology of those animals which, in their embryonic development, repeat the inferior forms from which they are derived, thus reflecting the general evolution of living beings. It was therefore to the embryology of lower multicellular beings that Metchnikoff turned, in order to endeavour to reconstitute their origin and to show the link between them and unicellular beings.

We know that the ovule or primitive genital cell of every animal may be compared to a unicellular organism. After fertilisation the egg undergoes consecutive divisions or segmentation; each segment constitutes a new cell, and their aggregation forms a hollow sphere called a blastula, which is similar to a colony of unicellular beings. The blastula differentiates itself into embryonic layers, the ectoderm, endoderm, and mesoderm already mentioned.

In the majority of animals the origin of the first two layers, ectoderm and endoderm, is due to the invagination of one of the poles of the blastula; the invaginated part of the walls forms the internal layer, the endoderm, and lines the cavity produced by invagination; this cavity thus becomes a digestive cavity. This stage of development, called gastrula, is similar to a cup with a double wall, of which the outer is the ectoderm and the inner the endoderm.

This stage, discovered by Kovalevsky, is to be found in the evolution of most animals and corresponds to the adult stage of some of them. It was consequently considered as the primitive type of multicellular beings.

Haeckel founded thereupon his theory of the gastrÆa, according to which the common ancestor of animals was a lower animal, now disappeared, and similar to that stage of development. He therefore gave to this hypothetical animal the name of gastrÆa.

Metchnikoff, however, discovered among primitive multicellular animals, such as sponges, hydroids, and lower medusÆ, a stage of development still more simple than the gastrula; this stage is without a digestive cavity and only assumes the gastrula form in its ulterior evolution. He also made the remarkable discovery that, in the most primitive multicellular animals, the endoderm is formed, not by means of invagination, but by the migration of a number of flagellated cells from one pole of the wall of the blastula into the central cavity. These cells draw in their flagellum, become amoeboid and mobile, multiply by division, fill the cavity of the blastula, and become capable of digesting. They originate the digestive cells of the complete organism and give birth to the mesoderm, which explains how the latter comes to contain a number of devouring cells even though these do not constitute digestive organs properly so called. Metchnikoff gave to that stage the name of parenchymella, for the migrating cells constitute the endoderm in the condition of a parenchyma.

The invariable presence of this stage in the simplest multicellular animals, the primitive amoeboid state of the endodermic cells, cases of ulterior transformation of the parenchymella into the gastrula form in certain animals, the absence of a differentiated digestive cavity,—all that proved, according to Metchnikoff, that the parenchymella is more primitive than the gastrula, and is therefore entitled to be considered the prototype of multicellular beings.

He saw a confirmation of this in the fact that primitive adult animals also have no digestive cavity but merely an intracellular digestion (sponges, turbellaria).

He concluded that the common ancestor of multicellular beings was a being constituted by an agglomeration of cells without a digestive cavity, but endowed with intracellular digestion, like that of the “parenchymula” stage of development. He therefore gave to that hypothetical ancestor the name of parenchymella.

Later, in 1886, he definitely formulated his theory of the genesis of multicellular beings, and having already stated the phagocyte theory, he substituted for the name parenchymella that of phagocytella, which indicated at the same time the primitive mode of digestion of that hypothetical ancestor.

Reduced to its simplest form, it presented, according to Metchnikoff, a certain analogy with a colony composed of unicellular beings of two kinds: the first, flagellated, forming the external layer, and the others, amoeboid, occupying the centre of the colony and capable of digesting.

It may be interesting to mention here that, in this hypothetical description, Metchnikoff foresaw the existence of similar, but real, beings discovered a year later by Saville Kent, namely, the flagellated colonies of Protospongia.

Thus the link between the unicellular and the multicellular beings could be constituted through the intermediary of flagellated colonies on the one hand and, on the other hand, of beings similar to a phagocytella. The indivisible colony became the multicellular individual.

While studying the genealogy of beings, Metchnikoff continued his researches on intracellular digestion. In 1879, at Naples and at Messina, he was able to establish the fact that the mesodermic cells of many larvÆ of Echinodermata and Coelenterata, endowed with a digestive tube, nevertheless contained strange bodies. Therefore, even complicated organisms with a differentiated digestive system could still contain at the same time some primitive cells with an autonomous digestion.

All these researches on the unity of the origin of multicellular beings and their morphological elements, and also those concerning intracellular digestion, were gradually preparing Metchnikoff’s mind for the conception of the phagocyte theory.

We spent the summer of 1880 with my family in the country. The cereals were invaded by a harmful beetle, the Anisoplia austriaca, which was devastating the country. Metchnikoff took the study of this scourge to heart and tried to find a remedy. He had, the preceding year, observed a dead fly enveloped with a sort of fungus which had evidently been the cause of its death. Hence he conceived the idea that it might be possible to combat harmful insects by provoking epidemics among them. He now returned to this idea; on dead bodies of Anisoplia he found a small fungus, the muscardine, which was invading the insects by means of filaments, and he succeeded in infecting healthy beetles.

At first he confined himself to laboratory experiments; then a great landowner, Count Bobrinsky, placed experimental fields at his disposal. As the acquired results were very encouraging, Metchnikoff, forced to leave the neighbourhood, left a young entomologist in charge of the application of his method. So far as he himself was concerned, this study proved the starting-point of his researches on infectious diseases.