Preliminary remarks on immunity in animal kingdom 47 



refractory or not very susceptible animals, we always observe a local 

 reaction in the form of inflammation, accompanied by the appearance 

 of white corpuscles. Gradually the organisms disappear from the 

 point at which they are introduced ; the exudation becomes sterile 

 and ultimately is completely absorbed. Numerous researches, which 

 will be set forth in the succeeding chapters, have, indeed, demon- 

 strated the remarkable analogy that exists between the disappearance 

 of the micro-organisms from the refractory animal and the resorption 

 of corpuscular elements or of animal cells. 



The analysis of the phenomena of this resorption will help us 

 considerably in our study of immunity against micro-organisms. 

 When in any part of the animal organism a collection of pus, an 

 effusion of blood, or any other organic lesion is produced, these lesions 

 are usually repaired after the lapse of a longer or shorter interval. 

 In those cases where the cells retain their integrity, they are taken 

 into the lymphatic vessels and then pass into the circulating blood. 

 In the course of his researches on the transfusion of blood, Hayem 1 

 observed "that blood injected into the peritoneum is absorbed un- 

 altered and passes with its anatomical elements into the general 

 circulation." He was able to demonstrate "that the lymphatic 

 channels play an important part in this absorption." Lesage of 

 Alfort 2 confirmed this result. He found that in the dog " one hour 

 after an abundant haemorrhage into the peritoneum, induced ex- 

 perimentally, the red corpuscles commenced to pass freely, without 

 alteration and in very large numbers, into the thoracic duct." I have 

 observed a similar resorption of the red blood corpuscles of the 

 guinea-pig when injected into the peritoneal cavity of other indi- 

 viduals of the same species. The white corpuscles can also be taken 

 up by the lymphatic vessels without being modified in any way. At 

 the end of an inflammatory reaction of feeble intensity, set up in 

 cold-blooded animals, especially in the tadpole, the direct passage 

 of leucocytes from the exudation into the lymphatic system may be 

 observed. 



The examples I have just cited are, however, quite exceptional. [51] 

 In the great majority of cases the cellular elements that are under- 

 going resorption are seized by the amoeboid cells and are taken into 

 their substance. Even in the resorption of the red corpuscles, lying 

 free in the peritoneal cavity of the same species of animal, a certain 



1 Compt. rend. Acad. d. Sc.. Paris, 1884, t. XCVHI, p. 749. 



2 Compt. rend. Soc. de biol, Paris, 1900, p. 553. 



