9 
In regard to his third question I think that the results obtained at 
the Hygienic Laboratory with the pigs raised here show that in our 
guinea pigs, at least, insusceptibility to diphtheria toxine is very rare. 
I am inclined to think that the influence of artificial selection in breed- 
ing is of slight importance if previous treatment of the breeders with 
the diphtheria toxine-antitoxin mixture can be excluded for several 
generations back. I can conceive that by the selection of breeders 
who have shown a special resistance to diphtheria toxine a very resist- 
ant race of pigs may be bred. 
It is not improbable that dealers and breeders of guinea pigs may 
buy at times used guinea pigs from persons engaged in work with 
diphtheria antitoxin and thus introduce unknowingly into their stock 
toxine-resisting pigs. 
The first experiments to immunize animals during pregnancy against 
pathogenic bacteria were positive.® Chauveau found that the young 
of sheep so immunized were immune to anthrax, and like results were 
arrived at by Arloing, Cornevin, and Thomas in symptomatic anthrax. 
Ehrlich was the first to study the problem methodically, and his 
results have been confirmed and stand. He used mice that had ac- 
quired a high degree of antitoxic immunity through systematic 
feeding of ricin, abrin, and robin. He showed that the male (sperm) 
element was incapable of transmitting the immunity. 
Ehrlich used female animals that were immune before becoming 
pregnant. By using animals that were being immunized during preg- 
nancy his results were interpreted as negative, inasmuch as positive 
results could not be referred to an active intra-uterine immunization 
of the fetus. In all of these cases his results were positive in that 
about four weeks after birth a definite immunity was demonstrable. 
About one and a half months after birth there still remained some 
undoubted immunity, but in the course of three months all traces had 
disappeared. 
This short immunit} T in the progeny of mothers was considered as 
passive immunity and rested on the transmission of antibodies from 
the mother. Against inheritance in the strict sense there was the fact 
that there was absolutely none present in the grandchildren of immune 
mothers. 
Ehrlich, therefore, concludes that neither sperm nor germ transmits 
the immunity and so no inheritance in the strict sense takes place. 
Ehrlich, b}^ his “mother exchange 11 experiment, showed that the 
antitoxins furnished in intra-uterine life did not long (21 days) remain 
in the young organism. He showed positively that the milk was the 
«The above summary of a part of the literature upon the influence of heridity in 
immunity is largely taken from the article by Morgenroth in Handbuch der patho- 
genen Mikroorganismen, 4 bd., p. 784. Those interested will find this an excellent 
discussion of the subject with bibliography. 
1184— No. 30—05 2 
* 
