Immunity acquired by natural means 447 



Vaillard 1 and Remlinger 2 upon a whole series of infective diseases 

 and intoxications, such as diphtheria, cholera peritonitis, anthrax, 

 experimental typhoid septicaemia, etc., showed conclusively the 

 correctness of Ehrlich's results. Well- vaccinated males, even when 

 hypervaccinated, never transmit their immunity to their descendants. 

 This acquired property, like so many others, is not hereditary in the 

 strict sense of the word. The females, on the other hand, with rare 

 exceptions, transmit their acquired immunity to their young, but 

 this transmission can in no way be attributed to the ovum ; it is here, 

 then, no longer a question of hereditary immunity properly so called. 

 According to Ehrlich the female furnishes in her blood plasma the 

 antitoxin which passes into the circulation of the foetus. In all 

 respects this is allied to the so-called passive immunity (or antitoxic 

 immunity of von Behring). It is due entirely to the direct intro- 

 duction of antitoxin, manufactured by the cells of the maternal 

 organism, into the body of the progeny. The living elements of the 

 foetus play no part in it, and it is for this reason that the antitoxins 

 a-nd immunity in the new-born animal disappear so very rapidly, 

 within a few weeks after birth. Wernicke accepts the views of 

 Ehrlich in their entirety. He found that the immunity of female 

 guinea-pigs was transmitted to the new-born animal ; but this [469] 

 hereditary transmission was exhausted in a single generation ; it was 

 not found in the second generation. Wernicke was able to demon- 

 strate that the refractory condition in guinea-pigs, born of mothers 

 vaccinated against diphtheria, persisted for three months. Vaillard 

 found that it was retained in certain cases for an even longer period, 

 up to the fifth month. On one occasion he even observed the 

 transmission of the immunity to a second generation. A female 

 guinea-pig, born of a mother immunised against tetanus, gave birth 

 to a young one which, when tested a month after birth with a ten 

 times lethal dose of the toxin, contracted merely a slight tetanus. 



From this fact, as well as from the fact that the immunity of the 

 young ones bora of vaccinated mothers persists longer than does that 

 conferred by the injection of antitoxic serum, Vaillard concludes 

 that there exists a kind of hereditary immunity which is " fixed " by 

 the cells. He thinks that not only the antitoxins and other anti- 

 bodies but also certain living elements, especially the leucocytes, are 

 able to pass from the maternal blood into that of the foetus and to 



1 Ann. de I'Inst. Pasteur, Paris, 1896, t. x, p. 65. 



2 Ann. de I'Inst. Pasteur, Paris, 1899, t. xiri, p. 129. 



