Immunity against pathogenic micro-organisms 133 



as that by which the resorption of the red corpuscles of the goose 

 ,^^kes place when they are injected into the blood of cockchafer larvae. [141] 

 I^Bu both cases the foreign bodies are ingested and destroyed by the 

 ^»ucocy tes of the blood ; this act of resorption, however, taking a very 

 ^^ng time. 



Although the leucocytes of the larvae of the rhinoceros beetle 

 exhibit a positive chemiotaxis for the bacillus, these same cells 

 behave in a very different fashion in presence of the cholera vibrio. 

 Very small quantities of this vibrio, when injected into the blood of the 

 larvae, give them a fatal disease : the vibrios excite in the leucocytes 

 a negative chemiotaxis and flourish without hindrance in the blood 

 plasma. The larva is soon transformed into a culture vessel and the 

 numerous vibrios that develop in it cause the death of the animal. 



The difference in action of the two bacteria cannot be explained 

 by any corresponding difference in their mode of life in the blood. 

 Removed from the organism the blood plasma of the white larvae of 

 the rhinoceros beetle is a culture medium just as favourable to the 

 growth of the anthrax bacillus as to that of the cholera vibrio. 

 Moreover, the former of these micro-organisms is quite capable of 

 setting up a fatal disease in other representatives of the class of 

 Insects. Kovalevsky^ has discovered in the house cricket four phago- 

 cytic organs, with a great appetite for all kinds of foreign particles 

 that may penetrate into its body. The blood of mammals, when 

 injected below the skin of the cricket, is rapidly absorbed by the 

 cells of the four "spleens" (for so Kovalevsky designates these 

 phagocytic organs). The resorption of the red blood corpuscles goes 

 on within these phagocytes owing to their power of intracellular 

 digestion. When Kovalevsky kept crickets at a temperature of 

 22° — 23° C. and injected them with anthrax bacilli he noted that 

 these bacilli also were ingested by the cells of the spleens. There 

 was, thus, no manifestation of negative chemiotaxis of these elements 

 towards the bacillus. The ingestion of the bacilli by the phagocytes 

 was not sufficient, however, to protect the animal. The bacilli re- 

 produced themselves rapidly in the blood fluid; the intracellular 

 lacunae of the spleens were full of them and the crickets quickly 

 succumbed to the infection. 



Nevertheless these crickets are quite capable of resisting certain 

 other bacteria. Balbiani^ has shown that they are refractory to[i42] 



1 Bull. Acad. d. sc. de St Peter sh., 1894, t. xiir, p. 437. 



2 Compt. rend. Acad, d, sc.y Paris, 1886, t cm, p. 952. 



