D. L. MACKINNON 
181 
In M. cetoniae the “ outer nuclear network ” is “ poor in chromatin ” 
(Jollos), and Hamburger finds that the flagella of this species show a 
tendency to inequality in length, and the development of a “Schlepp- 
geissel.” M. melolonthae, on the other hand, is described as having a 
“ wohlentwickelten chromatinreicheren Aussenkern ” (Jollos), and, ac¬ 
cording to Grassi, the flagella are of approximately equal length. So 
far as I can judge from the scanty indications in the literature, the 
flagellate from Tipula may be placed, at least provisionally, in Grassi’s 
species, M. melolonthae, from which it differs only in its somewhat 
smaller size and the frequent presence of extra-nuclear siderophilous 
granules. 
Fig. 12. Division stage of Monocerconionas from Tipula. 
The division stages (Fig. 12), so far as I have studied them, agree 
on the whole with Hamburger’s account for M. cetoniae. 
This flagellate occurs in about 75 “/o of the infected larvae. I have 
frequently observed what I consider to be its cysts. 
3. Polymastix. It is interesting to find that, as in Melolontha 
(according to Grassi (1882) and Hamburger (1911)), and in Cetonia 
(according to Hamburger (1911)), the Monocei'comonas of Tipula is 
usually accompanied by a Polymastix. 
This organism, which occurs sometimes in vast numbers, is a pear- 
shaped flagellate often forked or otherwise “ deformed ” posteriorly. The 
dimensions vary from 7/rx4;U.tol5yU.x 6'5 fi (Figs. 13 and 14). Four 
long flagella, approximately equal in length, spring from the anterior 
