448 Chapter XIV 



transmit to it the properties acquired by the mother. At this point 

 we may recall the facts demonstrated by von Behring and Ransom 

 that antitoxin persists much longer in the blood of an animal 

 when it is introduced with the serum of the same species. (We 

 have described these observations in Chapter xii.) Now, since in 

 hereditary transmission the antitoxin passes over with the blood 

 plasma of the same species, whilst in the experiments on antitoxic 

 immunity it is generally injected with the serum of a different species, 

 it is easy to understand that the former should persist for a longer 

 period than the latter. It is, therefore, very probable that this 

 immunity of the offspring from vaccinated mothers is not in any way 

 a case of true hereditary immunity, but is due simply, as maintained 

 by Ehrlich, to the passage of ready prepared antibodies from the 

 mother to the foetus. In the immunities against diphtheria and 

 tetanus we have the direct passage of antitoxins ; in transmitted 

 immunity against infection by the vibrios of Koch and Gamaleia, 

 so carefully studied by Vaillard, we have, very probably, the passage 

 of corresponding fixatives from the mother to the foetus. 



Dzierzgowsky 1 in a recent study on hereditary immunity denies 

 [470] the passage of antibodies and toxins through the placenta. He 

 thinks that the foetus does not acquire its immunity through the 

 blood of the mother, but at a very much earlier period. The ovum 

 contained in the Graafian follicle would, according to this observer, 

 come in contact with a fluid very rich in antitoxin, whence it might 

 imbibe the necessary amount of this antibody to ensure the immunity 

 of the new-born animal. Dzierzgowsky bases this opinion on experi- 

 ments in which antidiphtheria serum injected into pregnant goats and 

 idogs did not produce any antitoxic power in the blood of the foetus. 

 But in the experiments on these animals the injections consisted 

 of the serum of the horse a different species. This must modify, 

 profoundly, the conditions of the passage of the antitoxin through 

 the placenta. 



Dzierzgowsky made a single experiment upon a mare, immunised 

 with diphtheria toxin, and its foal. Whilst the serum of the former 

 was markedly antitoxic, that of the foal did not possess this property 

 in the slightest degree. Hence the conclusion that the antitoxin of the 

 mother had not passed into the blood of the foetus. But the blood of 

 the foal was not withdrawn until some ten months after birth. Now, 

 as the so-called hereditary immunity only lasts for a very short time 

 1 Arch. d. Xci. biol., St Petersbourg, 1901, t. vm, p. 211. 



