THE ANIMAL PARASITES 
Table 27. 
639 
Mammalia 
Aves 
Intestines 
per cent. 
9.0 
3.7 
2.3 
1.5 
1.0 
1.0 
0.5 
Blood 
per cent. 
6.5 
Stomach 
Intestines 
3.5 
Peritoneum 
Proventricle 
Air sacs. . 
1.7 
Blood 
1 3 
Lungs 
Liver 
Gizzard 
03 
Muscles 
0.3 
Liver 
Scattering 
0.4 
Total 
Total 
20.0 
14.0 
The effect of this is at first sight startling in that it 
places the blood parasites of birds so far in the fore, but it 
must be at once recalled that the inquiries upon the blood 
parasites were much more searching — microscopic, than 
in the case of the other organs. If similar methods were 
applied to the others their percentage of parasitism might 
be notably raised — particularly that of the intestines. 
Special Paeasitologic Considerations. 
At this point the statistical considerations of parasit- 
ism will give way to descriptions of certain specific inf est- 
ments that have given us more or less concern. 
The occurrence of single parasitic varieties or of well 
known species in an isolated host may occasionally be of 
practical importance, but usually they amount to little 
more than an academic study, whereas the repeated dis- 
covery of single parasitic kinds, or inf estmeiit of similar 
hosts, especially when grouped, raises the matter to a 
very practical level demanding attention. Such findings 
being not infrequent in our experience, it has been possi- 
ble to study our material in a manner designed to show 
the frequency of various parasites in a certain host, the 
susceptibility of certain animals to parasites in general 
and the inf estment of dissimilar hosts by the same para- 
site. The more important of these now follow. 
