6 
THOMPSON YATES LABORATORIES REPORT 
during the process of immunizing there are formed in the specific sera two substances, one to 
cause the agglomeration and another to inhibit movement, for this latter quality is nearly as 
characteristic of such sera as the former. 
If this agglutinative property carry with it a proportionate amount of immunity, then 
a considerable number of individuals are slightly immunized against typhoid, against cholera, and 
probably also against other diseases. 
It cannot yet be considered settled whetlier this property is inherited or acquired. Experi- 
ments on animals seem to show possibility of inheritance (14^), but if in these experiments 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 instance 
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 per- 
centage 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 figures. Anyway, in light of these differences of hasmic properties, statistics 
on the relative immunity (if it exists) of the cliildren 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 immunizing 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, viz., about sixteen days after 
infection. This may be taken to be about the time when the contest between organism and 
micro-organism seriously begins. In cholera, with its much shorter incubation period and rapid 
development, we should expect to, and actually do, find the reaction earlier. 
If the normal agglutinin in the blood is of a non-specific character, then an attack ot 
enterica produces an entirely new substance and does not add to what is already present, 
because the effect of the serum on cholera vibrios and coli bacilli remains the same, only that 
on typhoid bacilli is increased. 
The rate of agglutinin production varies in different cases as might be expected, and there 
is also a remarkable variation from day to day in the agglutinative power of the serum. These 
variations can hardly be entirely due to experimental errors. In immunizing animals I have often 
noticed that the agglutinative power seemed to increase irregularly. Moreover, it is known that 
