28o 
cent, of the corpuscles are infected, or in severe cases 
as many as ten per cent. Besides typical pear-shaped 
parasites, round and amoeboid forms occur. Free 
parasites also are not uncommon in severe cases. 
Cattle shewing emaciation, staring coat, etc., often 
shew parasites scantily. 
Post-mortem .—The tissues are oedematous and 
icteric. The spleen and liver are much enlarged. The 
kidneys are oedematous and haemorrhagic. The 
lymphatic glands are oedematous and haemorrhagic 
as in other forms of piroplasma affection. The serous 
membranes of various organs shew petechiae. The 
kidneys may have fifty per cent, upwards of red cells 
infected. Parasites are also numerous in the capil¬ 
laries of the heart, choroid plexuses, pia mater and 
brain. 
Culture. —Miyajima states that by adding a little 
defibrinated blood to ordinary bouillon kept at 20° 
to 30° C., trypanosomes develop, and further, that 
these give rise to piroplasmosis on injection. 
Transmission. —(1) Is easily effected by intravenous 
or subcutaneous inoculation ; the blood of recovered 
animals is also infective. 
(2) The following ticks are known to be carriers. 
The adult takes infection, the larva gives infection :— 
M. annulatus {vide p. 324), in America, Africa, etc. 
M. australis , in Australia. 
I. ricinus (= reduvius ), in Europe. 
P. bovis. —According to some observers this 
European form differs from P. bigeminum : (1) The 
parasites are plumper ; (2) The pears are smaller ; 
(3) The disease is more benign. 
Development in the Tick (Koch).—The parasites 
leave the red cell and become rather long and club- 
shaped (Fig. 91). At the clubbed end there is a large 
