652 DISEASE IN WILD MAMMALS AND BIRDS 
several instances F. gracilis has been the species identi- 
fied, always inhabiting the peritoneal cavity, and in one 
instance also the lung. Microfilaria were always present 
in the blood. We have never seen lymphangitis or 
elephantiasis in our filarial cases. 
Blood Parasites. — I justify this paragraph on the 
basis of the usefulnes it might have in the clinical direc- 
tion, for while the taking of blood specimens is not as 
easy as with man it can still be done with some animals. 
From time to time we have encountered blood parasites 
in this Garden, but the large numbers occurring in the 
experience of special searchers in the London Garden 
and Plimmer's particular interest in this direction make 
their data much the more valuable. In one report of 6,430 
animals examined he found 7 per cent, infested with blood 
parasites of one sort or another. I have constructed the 
foregoing table (28) from his various reports to show 
which animal classes were affected by the several 
blood parasites. 
This table (28) brings out that considering them as a 
whole and without respect to host, just as the animals 
come day in and day out to the autopsy table, blood 
parasites ^\^.ll be met in 6.7 per cent, of all cases. They 
are seen most commonly in the form of hemogregarines 
of reptiles (2.5 per cent, of all animals and 12 per cent, 
of all reptiles) while microfilaria run a close second, being 
found in 2 per cent, of all animals but much more 
commonly in birds. Hemoproteus of birds while ranking 
third, should be emphasized on account of its acknowl- 
edged blood-destructive properties. The remaining infes- 
tations were too infrequent to be useful statistically. 
Turning to individual groups of blood parasites, micro- 
filarice of birds deserve special comment. They occurred 
four times more often in birds than in other animals, or, 
put in another way, one out of eveiy twenty-two birds 
was affected, and only one out of every ninety other 
animals. The high figure for birds is significant in rela- 
