502 NOTES ON SOME PARASITIC PROTOZOA, 



organism in question is probably rare, since, although over a. 

 hundred blood-films from rats and mice have been examined here, 

 on no other occasion has it been detected, though Trypanosoma 

 lewisi Kent, is not uncommonly met with here in 31. decumamiSj 

 M. rattus and M. alexandrinus. 



As was mentioned by Balfour, the parasite infests the extra- 

 nuclear part of the mononuclear leucocytes. He found it in the 

 blood from the heart, liver, and spleen, but not from the kidney 

 and bone-marrow. This agrees exactl}^ with what we have seen,, 

 though smears from the spleen showed ver}"- few forms. Encap- 

 suled hiemogregarines (tigs. 10-11) were present in the plasma from, 

 the heart and liver, having been set free by the mechanical 

 destruction of the parasitised cell in making the smears. Unen- 

 capsuled free forms were not seen, nor were any segmenting 

 stages (schizogony) detected in sections of the liver, kidney and 

 spleen in both West Australian and Sydney specimens. Only a 

 few young parasites were seen (fig. 8). They did not possess a 

 capsule. The shape was mostly slightly crescentic ; both 

 extremities were blunt, one usually being somewhat wider. Th& 

 nucleus was situated either centrally or a little nearer one end. 



The commonest type Avas a more or less oblong encapsulecJ 

 form representing an adult sporont. The size was from 6-1 0/z. 

 long by 2-5 wide. There is thus a greater variation in size than 

 that noted by Balfour, who stated the measurements to be- 

 between 9 and 10'5/x long by 4-5 broad. As a rule the parasites, 

 were not crescentic, though such forms were not rare (fig. 10)^ 

 The usual shape was that of a fairly solid body, the middle of 

 which was as wide or only slightly wider than each end, the ends- 

 being of the same size and very bluntly rounded off (figs. 4-7). 

 In one instance the organism closely resembled in form certain: 

 hsemogregarines from the erythrocytes in snakes, there being a. 

 somewhat wider anterior end gradually tapering into a narrow 

 posterior end which was bent round to form a " tail "' (fig. 3), th& 

 whole animal being surrounded by a wide capsule. Another fact 

 worth noting in reference to this specimen, which was seen in a 

 smear from the liver, is that the host-nucleus was divided into 

 two quite separated portions. 



