292 Chapter IX 



" cholera antibody ") At a period when the serum as yet exhibited 

 an insignificant protective power or none at all, the extract from the 

 spleen often exerted an action of the most marked character. In an 

 experiment in which the rabbit was killed 48 hours after the injection 

 of the vibrios, 0*3 c.c. of the serum was incapable of preventing fatal 

 infection of a guinea-pig, whereas 0'03 c.c. of an extract of the spleen 

 exerted a marked protective effect. From this and similar experi- 

 ments, Pfeiffer and Marx conclude that the spleen is the principal 

 source of the protective substance. In order to verify this observation 

 they injected killed cholera cultures into rabbits which had previously 

 been deprived of their spleens, but the asplenic rabbits still produced 

 the same amount of protective substance, and these two observers 

 were led to conclude that the lymphatic glands and the bone-marrow 

 might also serve as the sites of origin of this substance. 



It is only during the first few days, however, that these organs 

 exhibit a protective power greater than that of the blood. Three or 

 four days after the injection of the vibrios the blood serum becomes 

 richer in protective substance; the organs contain much less of it. 

 This condition is maintained for some time, after which the blood in 

 turn begins to get impoverished. 



Pfeiffer and Marx put to themselves the question : Is the marked 

 protective power of the spleen due to the production of preventive 

 substance by this organ, or is it to be explained by an accumulation 

 in the spleen of this substance manufactured elsewhere? With the 

 [307] object of obtaining an answer to this question they injected protective 

 serum from other individuals into rabbits, when they found that the 

 protective substance showed not the slightest tendency to accumulate 

 in the spleen. These authors were compelled to conclude, therefore, 

 that the spleen and other haematopoietic organs (lymphatic glands 

 and bone-marrow) are the real seats of the production of the 

 protective substance. We may add that these organs are also the 

 phagocytic organs par excellence, that is to say, the centres which 

 serve not only for the development of phagocytes but which contain 

 a large number of the adult elements capable of exercising the 

 phagocytic function. 



Almost simultaneously with Pfeiffer and Marx, A. Wassermann 1 , in 

 collaboration with Takaki, undertook similar researches on the origin 

 of the substance protective against the typhoid cocco-bacillus. The 



!' BerL klin. Wchnschr., 1898, S. 209. 



