533 
chest, whilst in fifteen minutes the red cells in most of them were 
completely agglutinated, numerous clumps of various sizes being 
visible in the clear serum. The reaction was also distinct in many 
of the tubes kept at the laboratory temperature, but it was neither 
so marked, nor did it occur so quickly as in those subjected to the 
lower temperature. As before, no agglutination—or only- 
occasional lv a trace — was observable in the tests which had been 
placed in the incubator at 37 0 C. 
A large number of similar experiments were subsequently 
performed with the blood of monkeys, donkeys, goats, dogs, 
rabbits, guinea-pigs, and rats infected with various strains of 
trypanosomes. As a rule, it was found that a marked degree of 
agglutination only resulted when the temperature of the mixture 
of serum and red cells was lowered. Very exceptionally slight 
traces of agglutination were also seen in the tests carried out at 
37 0 C., but these could not be compared with the intensity of the 
reaction at low temperatures. 
Quite frequently a well-marked auto-agglutination was found 
to occur, at 0° C., in the control tests made with the blood of normal 
animals. I shall return to this important point later. 
Iso-agglutination .— A series of experiments were undertaken 
with a view to ascertaining whether the sera of those infected 
animals which possessed the property of agglutinating t eu 0 
red cells were also capable of producing agglutination of the 
erythrocytes of other animals of the same species. n every case 
where auto-agglutination was present, iso-agglutination was found 
to occur when the serum of the infected animal was , a ^ 
red cells of another animal (either normal or infected) of the sam 
species. 
Analogous results were obtamed with the blood o f a ^eo| 
human trypanosomiasis in Major Rosss c mic in 
Cover-slip preparations of the blood of th.s case exhib.te™ 
degree of Lo-agglutmation during the six months he was rnnku 
observation. The following table gives the resute of an 
examination of his blood, drawn ten days before hrs death, 
auto- and iso-agglutinins. 
