THE PROTECTING LEUCOCYTES 



disappear. After having thus destroyed five or six 

 microbes they would cease, but after a short time re- 

 commence again. 



The observations of Metchnikoff made in Pasteur's 

 laboratory show that the avidity with which the sev- 

 eral forms of pathogenic bacteria are attacked by the 

 leucocytes varies with the immunity of the animal. 

 Thus the bacilla of Anthrax, that are rapidly fatal to 

 sheep, cattle, rabbits, etc., are seldom found in the 

 white globules after their hypodermic injection into 

 these animals, not appearing to have been devoured 

 by the leucocytes ; while under the same conditions 

 they abound in the leucocytes of the dog, and other 

 animals who have greater resistance power to the 

 disease. Metchnikoff gives as an axiom the statement 

 that " the more refractory an animal is to a given 

 disease, so in proportion are its phagocytes capable 

 of absorbing and destroying the microbes that cause 

 the said disease." Why is it, he asks, that the 

 afflux of the white corpuscles to the point attacked by 

 the microbes varies in the same animal with the specific 

 microbes present? This, he answers, is due to the 

 curious property that certain substances, when present, 

 cause an attraction and others a repulsion of the 

 Leucocytes; for instance, most chemical substances, 

 albuminoids, acids and alkalies, etc. He claims for 

 the leucocytes an obscure consciousness, at least, as 

 15 225 



