206 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



instantly fatal if administered at the first dose. 1 But the 

 explanation of this adaptation is not known in any case ; 

 there seems to be some similarity between it and the so- 

 called histogenetic immunity against organic poisons. 



It is in the fight against animal and vegetable poisons, 

 such as those produced by bacteria, by some plants and 

 by poisonous snakes, that the true adaptation of the 

 organism reaches its most astonishing degree. The pro- 

 duction of so-called " anti- bodies ' in the body fluids is 

 not the only means applied against noxious chemical 

 substances of this kind : the existence of so-called histo- 

 genetic immunity is beyond all doubt, and Metschnikoff 2 

 certainly was also right in stating that the cells of the 

 organism themselves repel the attack of living bacteria. 

 Cells of the connective tissue and the white blood cells, 

 being attracted by them as well as by many other foreign 

 bodies, take them in and kill them. This process, called 

 " phagocytosis " is of special frequency among lower animals, 

 but it also contributes to what is called inflammation in 

 higher ones. 3 And there are still other kinds of defence 

 against parasites, as for instance the horny or calcareous 

 membranes, employed to isolate trichinae and some kinds 

 of bacteria. But all this is of almost secondary importance 

 as compared with the adaptive faculties of the warm- 

 blooded vertebrates, which produce anti-poisonous substances 

 in their lymph and blood. 



1 Davenport, Arch. Entw. Mech. 2, 1895-1896, and Hausmann, Pfiiigers 

 Arch. 113, 1906. 



2 Lemons sur la pathologic comparee de V inflammation, Paris, 1902. 



3 The other steps or phases in the process of inflammation have also been 

 regarded as adaptive : the increased quantity of body fluid for instance is 

 said to serve to dilute poisonous substances. 



