July 27, 1916] 



NATURE 



445 



Lhey are brought in hundreds of thousands by the 

 process known as inflammation, but he also imme- 

 diately g-ave first-class importance to their recog- 

 nition by connecting them with Pasteur's great 

 discoveries as to the cause of infective diseases by 

 poisonous " microbes " which intrude into previ- 

 ously healthy organisms, and he further connected 

 his generalisation with Darwin's theory of the 

 origin of species by the natural selection of 

 favoured races in the struggle for existence. He 

 published in 1884 an essay entitled "The Struggle 

 of the Organism against Microbes," in which he 

 maintained the thesis that the phagocytes, univer- 

 sally present in multicellular animals, have been 

 developed and established by natural selection in 

 the animal organism as a protection against intru- 

 sive disease-causing bacteria. 



He was able in 1884 to observe and give illus- 

 trative drawings of a demonstrative case of the 

 activity of the phagocytes in the blood of a trans- 

 parent fresh-water flea (Daphnia) when it was 

 infected by a yeast-like parasite called Monospora. 

 This parasite frequently makes its way into the 

 blood of the water flea and, multiplying there, 

 often causes death. Metchnikoff watched with 

 his microscope and made careful drawings of the 

 phagocytes as he saw them in the living flea en- 

 gulfing and digesting the intrusive Monospora. 

 In some cases the phagocytes, in others the Mono- 

 spora, got the upper hand. Later when I knew- 

 him he had a small aquarium dedicated to the 

 cultivation of these demonstrative w-ater fleas and 

 their infective microbe. 



Having now determined to give up his zoologi- 

 cal and embryolc^ical researches in order to devote 

 the rest of his life to the development of his doc- 

 trine of "phagocytosis," Metchnikoff accepted the 

 invitation to become director of a new bacterio- 

 logical laboratory at Odessa, but, finding the con- 

 ditions there not favourable to his special work, 

 he relinquished the post in 1888 and, having for- 

 tunately been cold-shouldered in Berlin, came to 

 Pasteur in Paris^ who, thoroughly appreciating 

 the value of his work, gave him a laboratory and 

 every facility for his investigations in his own 

 institute, at that time located in the Ecole Normale, 

 rue Vaugirard. When a few years later the 

 Institut Pasteur was built in the rue Dutot 

 Metchnikoff was given a fine suite of laboratories, 

 lecture-room, and space for keeping animals, 

 and became sub-director of the institute a few 

 years ago. 



Young investigators now came in growing num- 

 bers to Paris in order to work in Metchnikoflf's 

 laboratory, and he pursued with triumphant suc- 

 cess, but not without opposition and sometimes 

 insult from the older and more ignorant medical 

 men, the establishment of his views as to the 

 essential importance of " phagocytosis " in resist- 

 ance to disease. Among his more fatuous oppo- 

 nents was a prominent English pathologist who 

 scornfully alluded to his views as " Metchni- 

 kof!ism."' 



In 1892 he produced as an illustrated volume, 

 with the title "The Comparative Pathology of In- 



NO. 2439, VOL. 97] 



flammation," the substance of a course of lectures 

 delivered at the Institut Pasteur. It is one of the 

 most delightful examples of scientific method con- 

 ceivable. It is essentially a careful and logical 

 presentation of minute observations arranged so 

 as to bring before the reader the evidence in 

 favour of his argument. He invariably followed 

 this method in the controversies in which he 

 necessarily engaged. He never recriminated ; 

 he never cited mere authority nor endeavoured 

 to falsify his opponent's statements by "smart" 

 word-play. He simply made new experiments 

 and observations suggested by his adversary's 

 line of attack, and so practically smothered 

 him by the weight of honest, straightforward 

 demonstration of fact. He showed that in 

 the lower rnimals the phagocytes are attracted 

 in hundreds by " chemiotaxis " to intrusive or 

 injurious bodies which occur in the tissues, and 

 then either enclose or digest them. He proceeded 

 10 show that in the vertebrates, where the immense 

 network of the blood-vessels is under the control 

 of the nervous system, "inflammation" is set up 

 as a curative process, and that the elaboration of 

 its mechanism has been established by natural 

 selection. A local arrest of the blood-stream is 

 produced by the ner\-e-control of the vascular sys- 

 tem, resulting in the out-wandering from the now 

 nearly stagnant blood of phagocytes chemically 

 attracted to an injured spot, where, arriving like 

 an innumerable crowd or army of scavengers, they 

 proceed to engulf and digest tissue which has 

 been killed by injury, and similarly to isolate or to 

 destroy and digest injurious intrusive substances, 

 prominent among which are infective poisonous 

 bacteria. 



Metchnikoff thus finally and conclusively "ex- 

 plained" the process called "inflammation." His 

 attention and that of his pupils was now given 

 for some years to the great question of "immu- 

 nity." How is it that some individuals are either 

 free from the attacks of parasitic micro-organisms 

 to which their fellows are liable, or, if attacked, 

 suffer less seriously than others do? To answer 

 this question is to go a long way to the solution 

 of the great practical question as to how to pro- 

 duce immunity to infective disease in man. It 

 involved the investigation of the chemical activi- 

 ties of the phagocytes, to the knowledge and theo- 

 retical understanding of which a great number of 

 highly gifted leaders of experimental inquiry — to 

 name only Ehrlich, Behring, and Almroth Wright 

 — have contributed in the most important way. 

 It is impossible on this occasion to enumerate or 

 even indicate the large series of investigations and 

 records of experiment now continuously produced 

 by Metchnikoff or by assistants under his imme- 

 diate supervision. The Annales de I'Institut 

 Pasteur are largely made up of these records and 

 discussions. In 1901 Metchnikoff produced his 

 great book on " Immunity in Infectious Diseases," 

 an English translation of which \\ as at once pub- 

 lished. The subject branched out into various 

 lines, such as are indicated by the names sero- 

 therapy, toxins and anti-toxins, haemolysis, opso- 



