June 28,' 1894] 



NA TURE 



195 



■definition of inflammation of course differs essentially 

 .from that adopted in pathological text-books, for Metchni- 

 •koff places the vascular phenomena in the second rank, 

 and reduces to a minimum the part played by the 

 nervous system. It must be acknowledged, however, 

 that the author brings forward a formidable array of 

 facts observed in the various branches of the animal 

 kingdom in order to place his theory on a sure footing ; 

 and he clearly establishes one point, namely, that inflam- 

 mation may take place without the blood-vessels or 

 nervous system playing any part in it. On the other 

 hand, a critic might object that, in the higher animals 

 at least, there are many forms of inflammation in which 

 the amoeboid cells take little, if any, part at all. The 

 proposition is, nevertheless, for the most part true, and 

 it has undoubtedly given us a key to the understanding 

 of many obscure points connected with the problem of 

 immunity against microbes. 



To a large extent the process of resistance of the 

 animal body against the invasion of micro-parasites 

 is due to the action of cells derived from the mesoblast. 

 This, Metchnikoff has demonstrated by a number of 

 extremely interesting experiments, and has shown that, 

 in vertebrate and invertebrate alike, this function is at all 

 times carried on. He and his pupils have proved that 

 it is a normal physiological function taking place in 

 certain parts of the body, such as the tonsils and the 

 Payer's patches of the intestine. 



The theory of Prof. Metchnikoff has not been 

 accepted by the majority of pathologists, and has 

 been treated with scant respect by many bacterio- 

 logists, more especially in Germany. In this country 

 it has, however, been received with greater favour, 

 and it is well that such a book should have been 

 translated by Dr. and Mrs. Starling. Indeed, for the 

 translation we have nothing but praise ; it is worded in 

 ■excellent English, and, what is more, the meaning of the 

 author is, with very few exceptions, exactly reproduced. 



It is interesting, however, to see how much of the work 

 is controversial in character, and one might almost wish 

 that Prof. .Metchnikofifhad not wasted so much time in 

 ■disputing the many rival theories which have since been 

 shown to be erroneous, and are no longer held even by 

 their promoters. The theory, for instance, that the 

 defence of the organism was due to the so-called bacteri- 

 cidal power of the serum, a theory which was defended 

 by so well known an observer as Dr. Klein, has now been 

 almost universally given up. Metchnikoff and his pupils 

 ■hit the right nail on the head when they proved that the 

 bactericidal action of the serum in b. test-tube was a very 

 •different thing from the action of the serum in the living 

 body. Indeed, it is difficult to understand how such a 

 notion should have received any favour, when not a single 

 fact could be produced to show that this bactericidal 

 action ever takes place in the human or animal body. The 

 experiments of Sanarelli, which seemed at one time to 

 support it, have now received another interpretation from 

 their author. When, later on, it was shown that the 

 bactericidal action of the serum irt immune animals was 

 very much more marked than in non-immune animals, it 

 was thought that a strong point had been scored against 

 the phagocytic theory ; but the discoverers of this fact 

 ^Messrs. Hehring and Nissen, had to confess that this 

 ^0. 1287. VOL 50] 



stronger bactericidal action was not always present in im- 

 mune animals, and that it occurred in some diseases only. 

 Lastly, the theory was finally buried when Metchnikoff 

 showed that this bactericidal action of the serum had no 

 power to check the reproduction of micro-organisms, and 

 that the immunity was produced by the action of the 

 despised amccboid cells. Indeed, to thinking patho- 

 logists, it was apparent from the first that a theory 

 based on the action of the serum was an impossible one, 

 for all the facts relating to serous effusion in the human 

 and animal body pointed to an opposite conclusion. In 

 the majority of cases, serous effusion produces no im- 

 munity, and, in many cases, the fact that a large quantity 

 of fluid is exuded from the vessels shows that the disease 

 must end fatally. 



Of the anti-toxic theory, which was promoted at one 

 time by Behring and his school. Prof. Metchnikoff speaks 

 with great respect ; but in a series of interesting pages 

 he shows how it does not apply to all cases, and that even 

 when the blood contains a large amount of anti-toxine 

 the patient nevertheless dies of the disease ; and con- 

 versely, that an animal maybe immune against a disease 

 without its blood having any anti-toxic power whatever 

 on the toxines secreted by the bacillus which is the 

 cause of the disease. 



Prof. Behring himself has now been obliged to give up 

 this theory, and it has been lately shown by Buchner and 

 others that, as a matter of fact, the serum of an immune 

 animal has no anti-toxic power at all, and that in such 

 cases the animal recovers owing to the rapidity with 

 which the immunity is produced. 



Of the other rival theories it is unnecessary to speak, 

 as Prof. Metchnikoft' has himself shown that a great 

 many facts which have been brought forward to support 

 them cannot be maintained. Of all the theories, 

 therefore, which have been thought to explain the 

 natural and acquired immunity of animals and man 

 against infectious disease, the phagocytic theory is the 

 only one which still holds the field, and, although it will 

 not explain all the phenomena of immunity, it is the only 

 one which is based on accurately observed facts, and 

 which will explain how microbes are destroyed in the 

 body. Moreover, those who will read the present book, 

 will see that Metchnikoff himself has always allowed that 

 probably there are other factors in the production of 

 resistance against infectious disease, but that the chief 

 factor was the part played by cells derived from the 

 mesoderms, and especially by the wandering amceboid 

 cells. 



OUR BOOK SHELF. 



The Camel, tls Uses and Managemtnt. By Major A. G. 

 Leonard. (London: Longmans, Green, and Co., 1894..) 



The author treats in this work of the management of 

 the camel in connection with military operations, the 

 result of his experience in India, Afghanistan, Egypt, 

 and the Sudan. He does not claim to have produced 

 a scientific essay on the animal, but rather to furnish 

 officers and others in charge of camel transport with a 

 practical description of the camel, his treatment and 

 management, so as to enable them to avoid the causes to 

 which the enormous mortality of baggage camels in 

 recent expeditions has been mainly due. .A.fter describ- 



