BLOOD AND THE IDENTIFICATION, ETC. 623 



It cannot yet be considered settled whether this property 

 is inherited or acquired. Experiments on animals seem to 

 show possibility of inheritance (14 d), but if in these experi- 

 ments the inoculations were made into the peritoneal cavity 

 there is an obvious source of error. In the few human 

 cases which I have been able to examine, the blood of the 

 child was usually inactive although that of the mother was 

 generally, sometimes even powerfully, active. In one in- 

 stance where the mother had had enterica five years 

 previously, the child's serum exhibited but very feeble 

 agglutinative power. In one case where the child was 

 born during an attack of enterica in the mother the serum 

 was very active, but in another it was not so ; possibly in 

 the first case the child was also passing through an attack. 

 If the specific agglutinins are inherited they should be found 

 fairly frequently in the sera of new-born children, especially 

 abroad, where a larger percentage of the population have 

 had either enterica or cholera. According to my own 

 observations, in Austria at any rate, a greater percentage 

 of adult than infant sera possesses this property, tending to 

 show that it is an acquired quality. It may be that a more 

 extended series of observations would reverse these fiofures. 

 Anyway, in light of these differences of haemic properties, 

 statistics on the relative immunity (if it exist) of the children 

 of " typhoid " parents would be of interest. 



It was natural to suppose, as the result of experiments 



on animals, that typhoid (or cholera) patients, who were 



thus passing through a natural Immunising process, would 



produce agglutinins in their blood. Observation showed 



this supposition to be correct, and vaccination experiments 



on man have confirmed it. In the latter case agglutinins 



have been observed in the blood already on the second day 



after injection (15^)- When the infection of typhoid takes 



place in the natural way owing to the smallness of the initial 



dose, the agglutinin Is not generally found In the serum 



until two or three days after the nominal commencement of 



illness, vis., about sixteen days after injection. This may 



be taken to be about the time when the contest between 



organism and micro-organism seriously begins. In cholera, 



42 



