568 Chapter XVII 



animals treated with the red corpuscles of another species was com- 

 menced, no one would have suspected that these researches would end 

 in the discovery of new methods for the recognition of human blood in 

 medico-legal researches, or in the interests of hygiene for the determi- 

 nation of the source of a milk. The cellular theory of immunity is, as 

 yet, of too recent date for us to claim the right to expect it to have 

 amongst its assets methods for purely practical application. Never- 

 theless, it has already been found to be of service in the investigation 

 of problems very closely affecting medical practice. Lord Lister, the 

 greatest surgeon of the nineteenth century 1 , asked himself how it was 

 that wounds could heal "by first intention under circumstances before 

 incomprehensible. Complete primary union was sometimes seen to 

 take place in wounds treated with water-dressing, that is to say, a 

 piece of wet lint covered with a layer of oiled silk to keep it moist. 

 This, though cleanly when applied, was invariably putrid within 

 twenty-four hours. The layer of blood between the cut surfaces was 

 thus exposed at the outlet of the wound to a most potent septic focus. 

 How was it prevented from putrefying as it would have done under 

 such influence if, instead of being between divided living tissues, it 

 had been between plates of glass or other indifferent material?" 

 " How were the bacteria of putrefaction kept from propagating in the 

 decomposable film ? Metchnikoff's phagocytosis supplied the answer. 

 The blood between the lips of the wound became rapidly peopled 

 with phagocytes which kept guard against the putrefactive microbes 

 and seized them as they endeavoured to enter. If phagocytosis was 

 ever able to cope with septic microbes in so concentrated and intense 

 a form, it could hardly fail to deal effectually with them in the very 

 [593] mitigated condition in which they are present in the air. We are thus 

 strongly confirmed in our conclusion that the atmospheric dust may 

 safely be disregarded in our operations ; and Metchnikoff's researches, 

 while they have illumined the whole pathology of infective diseases, 

 have beautifully completed the theory of antiseptic treatment in 

 surgery." (Rep. Brit. Ass., p. 27.) 



We may even attempt to increase phagocytosis in surgical opera- 

 tions, especially in those on the peritoneal cavity, by there setting up 

 an artificial aseptic inflammation, by means of various substances, 



1 "The Relations of Clinical Medicine to Modern Scientific Development," a 

 discourse delivered at Liverpool in September, 1896. Rev. scient., Paris, 1896, 

 4 e se>. t. vi, p. 481 ; [Rep. Brit. Ass. Adv. Sci., London, 1896, p. 3 ; Brit. Med. 

 Journ., London, 1896, Vol. n, p. 733]. 



