182 
Protozoa in Tipula 
end in two groups of two. The nucleus is of the same vesicular form as 
in Monocercomonas, containing a caryosome composed of a number of 
closely-massed chromatin granules, but with very little chromatin in the 
space between caryosome and nuclear membrane. As in the Mono¬ 
cercomonas the nucleus is surmounted, and in part surrounded, by a 
group of siderophilous granules. In well-stained individuals it is 
Fig. 1.3. Polymastix from Tipula. Large flagellate individual showing vesicular nucleus, 
extra-nuclear granules, axostyle, etc. 
Fig. 14. Polymastix showing a characteristic posterior deformity. 
generally possible to make out an axostyle of the same sort as in 
Monocercomonas, and bearing the same relation to the nucleus and 
basal granules^ In all these points, Polymastix and Monocercomonas 
resemble one another closely. The chief feature that distinguishes the 
1 In Polymastix the nucleus is usually placed further from the anterior end than in 
Monocercomonas. 
