246 
Cultivation of Piroplasma 
At the end of an hour the clear fluid contained some free motile 
pyriform bodies. Some of this fluid was now added to defibrinated 
normal dog’s blood and unstained preparations of the mixture thus 
obtained were examined. Although free swimming parasites were 
kept under observation, with one exception which we have previously 
described ( Journ . of Hygiene, 1906, Vol. vi. p. 632), none were seen to 
enter fresh corpuscles. 
In other experiments some of this fluid was mixed with normal 
dog’s corpuscles suspended in sodium citrate solution, and the mixture 
kept in the dark at room temperature for 20 hours. At the end of this 
time fresh preparations were examined and motile parasites seen, but 
none were found in corpuscles. Stained specimens confirmed the 
observations made on living preparations. 
Similar experiments were carried out with serum obtained from 
blood which was allowed to clot, with the same results. 
B. Dog’s serum containing motile pyriform bodies was added in 
small quantities to tubes containing rabbits’ blood corpuscles suspended 
in 4 °/o sodium citrate solution. Examinations of fresh and stained 
preparations showed that the parasites had not entered the corpuscles. 
C. The following experiments were undertaken to determine 
whether the parasites would live and multiply in the serum of infected 
animals. Shortly after death blood-stained serum from the heart was 
drawn up into tubes and centrifugalised. Two hours later the clear 
fluid showed many rounded parasites and a few actively motile pyriform 
bodies. After 17 hours a few rounded forms were found, but no motile 
parasites. 
Serum taken from coagulated blood was examined in the same way. 
This also showed some rounded forms and a few motile pyriform bodies 
after two hours, but no motile forms after 22 hours. 
D. Several experiments were made with defibrinated blood taken 
from the heart immediately after death. Some samples were kept in 
sealed tubes, and others in tubes plugged with cotton wool. Some of 
these tubes were kept in the ice chest, and others at room temperature. 
Examinations of fresh and stained preparations were made at various 
times with samples taken from the various layers into which the fluid 
separated. In all 15 experiments were carried out and the examina¬ 
tions were made at times varying between 17 hours and 69 days. 
Motile pyriform bodies were noticed up to 17 hour’s, but not later, and 
non-motile pyriform bodies were seen up to the third day. After this 
time all the free parasites seen were either rounded or in various stages 
