244 SCIENCE PROGRESS. 



It is consequently proved conclusively that even if there are 

 any protective bodies in the offspring the quantity derived 

 directly from the mother is almost nothing when contrasted 

 with the amount yielded by milk. The protective sub- 

 stances which are in the milk exist also in the blood serum, 

 since a normal susceptible mother is rendered immune and 

 will furnish a protective milk when the serum of an abrin- 

 resistant animal is introduced. 



Transference by milk of substances which are antago- 

 nistic to the tetanus toxine also occurs during the lactation 

 period. The protective serum of a horse was injected into 

 a suckling mouse, and after twenty-four to seventy-eight 

 hours this induced protection is found to exist also in the 

 young, and in confirmation of the well-known results of 

 Kitasato that tetanus when fully developed can be checked 

 by introduction of protective serum, Ehrlich has found that 

 tetanus developed in young animals can be absolutely 

 arrested by feeding them from a highly immune mother. 



Previous to these epoch-making experiments it was 

 believed that the blood was the chief, if not the exclusive, 

 vehicle of protective bodies, and the passage of these into 

 the secretions was unknown. The mamma, however, is the 

 only organ which secretes proteids to any extent, and it is 

 remarkable that the anti-bodies, which are generally re- 

 garded as very easy of decomposition, are capable of pass- 

 ing through the bowels unchanged and then enter the body. 

 Feeding experiments with the organs of immune animals 

 never confers immunity. 



In a later paper Ehrlich and Brieger (45) confirm the 

 previous investigations. They find that the milk of a goat, 

 which towards the end of pregnancy had been rendered 

 immune to tetanus by daily injections of thymus-tetanus- 

 bouillon mixture, which were slowly increased in strength, 

 possessed a high protective value. The milk secreted by 

 the animal showed, however, considerable fluctuations in 

 strength, but injected into mice conferred upon these 

 animals an immunity to inoculation with virulent tetanus 

 cultures, which was at least sixteen times above that of the 

 normal animal. Attempts to isolate the protective sub- 



