578 Proceedings of the Royal Society of Edinburgh. [Sess. 
Passive acquired immunity is likewise conferred to a very slight 
degree only, for the serum of treated rodents, even when it possesses a 
very high agglutination titre, fails to protect normal rabbits and guinea- 
pigs against infection, or even to modify the course of such infection. 
Agglutinating serum from larger animals appears to be no more potent. 
On the other hand, a certain degree of immunity is undoubtedly trans- 
mitted from the infected maternal parent to her offspring, for in both the 
infected dog and goat, although the micrococcus melitensis, minute though 
it is, does not traverse the placenta and so no actual infection occurs, an 
appreciable amount of specific agglutinin is transmitted to the pups and 
kids. But beyond a doubt other antibodies are also carried over, for 
although these animals are readily susceptible to infection with M. melitensis 
via the alimentary tract, and although the infected parent is secreting milk 
teeming with the micrococcus, which is taken by the suckling young, 
infection does not result during the period of suckling. The inference is 
therefore justified that the young are supplied with other antibodies besides 
the specific agglutinins which protect them from infection during the 
period of suckling. These statements are based, it is true, upon a limited 
number of observations, but at my suggestion Professor Zammit is continuing 
these experiments, with results which go far to support my conclusions. 
Animal. 
Examination of Parent. 
Examination of Offspring. 
Titre of 
Serum. 
M. melitensis 
in Milk. 
Length of 
Life. 
Titre of 
Serum. 
Recovery of 
M. melitensis 
from Tissues. 
Dog 8 
1 : 200 
Yes 
Pup a 
. • • 
• • • 
1 day 
1 : 10 
nil. 
„ ' b 
• . o 
1 day 
1 : 10 
55 
„ c 
• • • 
. . • 
14 days 
1 : 10 
55 
55 ^ 
. . . 
. . • 
14 days 
1 : 20 
55 
Dog 28 
1 : 20 
Yes 
Pup 
• • • 
• . • 
5 days. 
1 : 10 
nil. 
55 / 
• • . 
• . . 
5 „ 
1 : 10 
55 
55 9 
... 
... 
5 ,5 
1 : 5 
55 
Goat 3 
1 : 100 
Yes 
Kiel a 
... 
• • • 
17 days. 
1 : 50 
nil. 
,5 b 
... 
... 
17 days. 
1 : 20 
55 
This immunity, however, is only partial and temporary, being limited 
to protection against infection via the alimentary tract ; and to the period of 
suckling, for Jdie young are still susceptible to subcutaneous, intravenous, 
