reaction to take place. The third rat, however, lived longer than 
the controls, and in this case, if we eliminate the fact that it may 
have been a more resistant animal, we had the life prolonged bv 
the vaccine, which was given with an interval of one day between 
the doses. 
We attempted the same line of treatment in two guinea-pigs, 
but here again, we cannot say that we prolonged life. We now 
attempted to obtain results with a blood prepared when the 
trypanosomes were low in the peripheral blood, i.e., we tried a 
condition in which one would expect to find anti-bodies, and in 
addition to this the blood was rich in leucocytes. The first 
injection, given on the eighth day, produced a fall in the 
trypanosomes and a rise in leucocytes which was very marked. 
I he second injection was given on the thirteenth day, and again 
we obtained a fall (slight), but the leucocytes also fell. On the 
twentieth day we gave an injection of blood obtained from an 
animal when the trypanosomes were numerous; a very high rise took 
place and the animal died. This animal lived twenty-two days, 
i.e., we may conclude that we prolonged its life, and, indeed, the 
animal might have lived a longer period had we not on the twentieth 
day given too strong a dose of vaccine. We publish the chart of 
the last experiment (Rat 95), as it shows the rise and fall of 
the leucocytes in relation to the rise and fall of trypanosomes. It 
' v iH * JC n °ted, if we refer to chart of Rat 95, that after inoculation 
a ^ euco penia takes place, and when trypanosomes first appear in the 
peripheral blood we have the leucocytes increasing. Again, it will 
x* noted that when the trypanosomes are high in number that there 
ends to be a fall in the number of leucocytes, whereas when the 
trypanosomes are low in the peripheral blood there tends to be a 
mar -ed leucocytosis. We have noticed this relation between 
eucocytes and trypanosomes in many cases. 
e append tables of numbers of three untreated controls, viz., 
* s 1 4 » 15 and 16, and the tables of three rats treated with 
une of a blood rich in trypanosomes, viz., Rats 42, 43 and 44 
a " ' / astly ’ we append a chart of Rat 95 infected with 
( tsiense. Here the first two doses of so-called vaccine were 
P P e d from a rat when the trypanosomes were few in the 
C,1 P eral blood, and we note that a fall in the numbers took place 
