1893.] Bacteriology in its General Relations. 1063 
mals are open to the same objection. That the immunizing 
substance does permeate the entire body so that even the 
secretions are affected has been recently proven by the experi- 
ments of Ehrlich. He has recently shown that young mice 
may acquire immunity against that toxic alkaloid, ricin, by 
being nourished upon the milk of their mother, which has 
been artificially immunized. He obtained similar results with 
the tetanus bacillus, by immunizing a mother mouse with 
serum from a horse when the young were 17 days old. In 24 
hours, one of the suckling young was infected with virulent 
tetanus spores from which it experienced no ill effect, while a 
control died in 26 hours. Two and three days after the 
mother had been immunized, other of the young were also 
tested, and it was found in these cases that the immunity was 
also transmitted from the mother to her progeny. 
. If the injection of the immunizing substance into the body 
of an animal can so permeate the tissues as to reappear in the 
secretions in 24 hours, it would seem highly probable that the 
immunity claimed to be transmitted by inheritance might be 
regarded as passing directly from the mother to her young 
rather than by means of the germ plasm. 
The same objection applies to those cases where infectious 
diseases are claimed to have been transmitted. Wolff has 
recently subjected all of these cases to the closest examination, 
and he finds that only in a very limited number is there any 
probability that infection is ever transmitted from parent to 
progeny. In numerous cases of so-called inherited disease, he 
has actually determined lesions of the placenta, that allowed a 
direct passage of the germ. He claims that in no case has it 
been thoroughly proven that disease has been transmitted by 
ihe germ-plasm, although it is possible that either male or 
female generative cell may be diseased, and thus an infection, 
which he calls conceptional may take place. 
Ehrlieh has recently made some very interesting observa- 
tions that have a direct bearing upon this question of acquired 
characters. They possess the advantage of approaching the 
subject in a fundamental manner, and while they are not 
numerous enough to justify general conclusions, they are of 
