1910. ] Red Blood Cells in Trypanosomiasis. 247 
Technique—The blood was obtained from a convenient vein, and the 
defibrinated plasma separated from the red corpuscles at 37° C. in the 
manner already described. The red corpuscles were washed three times in 
warm saline solution, and finally a 5-per-cent. suspension made in 0°9-per- 
cent. sodium chloride solution. Equal volumes of the defibrinated plasma 
and red cell suspension were drawn up together into three fine pipettes 
which were then subjected to a temperature of 0°, 15°, and 37° C. respectively. 
The pipettes were kept in the vertical position, and the contents examined 
for auto-agglutination with the aid of a lens from time to time. It was 
found in the majority of cases that the test could not well be continued for 
longer than one hour, owing to the fact that in most cases the erythrocytes 
had subsided to a marked degree after the lapse of this period. At times 
the citrated plasma was substituted for the defibrinated plasma. The 
same precautions regarding temperature were taken, and only very small 
amounts of citrate solution (not more than a tenth of the volume of plasma) 
employed. The plasma obtained in this way frequently clotted, but the 
process was sufficiently retarded to permit of the previous separation of the 
red corpuscles. No appreciable difference between the agglutinating action 
of the defibrinated and citrated plasma was observed. 
The results of this investigation of normal blood for auto-agglutinin may be 
summarised by stating that small quantities of auto-agglutinin were found to be 
present in the blood of rabbits (14), guinea-pigs (4), goats (3), dogs (2), horses (4), 
donkeys (2), monkeys (Macacus rhesus) (2), and Cercopithecus callitrichus (2). 
Sometimes, especially in goats and guinea-pigs, the amount present was 
exceedingly small, and considerable care was necessary to demonstrate its 
existence. In these cases a larger volume of serum was used in proportion 
to the amount of red cells and the reaction allowed to proceed for a longer 
period. It is to be observed that clumping of the erythrocytes only occurred 
in the tests carried out at low temperatures, and not in those subjected to 
a temperature of 37° C. 
Relation of Auto-agglutinin of Normal Blood to that present in the Blood of 
Animals infected with Trypanosomes.—In this connection it may be remarked 
that in the blood of infected animals there exists a considerable excess of 
auto-agglutinin beyond that present in the blood of normal animals. It was 
found that diluting the defibrinated plasma of normal blood with twice its 
volume of normal saline solution usually sufficed to destroy its agglutinating 
action. On the other hand, it was often possible to dilute the infected plasma 
15- or 20-fold, and still obtain complete agglutination of the erythrocyte 
suspension. 
Lffect of Heat on Auto-agglutinin.—Different portions of the defibrinated 
