184 
Protozoa in Tipiila 
account given by Frl. Hamburger. But in iron haematoxylin prepara¬ 
tions wbere the ditferentiation is unsatisfactory, I get much the same 
homogeneous nucleus as she describes, and can see nothing of the 
axostyle. I am inclined to regard the Polymastix from Tipula as 
identical with the type-species Polymastix melolonthae (Grassi). 
Fig. 15. Polymastix in which the hinder end has lost its characteristic ribbed pellicle. 
Fig. 16. Polymastix in which the periplast is fraying off. Possibly some of these “ribs” 
may in this case be adherent bacteria. 
4. Hexamitus. In some 10 “/o of these infected larvae there occurs 
very sparingly^ a flagellate which is apparently Hexamitus intestinalis, 
or some very closely allied species (Fig. 17). It is of small size, 8 pxS /x 
being the maximum dimensions. Its mode of occurrence suggests that 
it is more or less a chance parasite, and that Tipula is not its true 
host. Hexamitus intestinalis has been recorded from such diverse 
animals as frogs, toads, tortoises, lizards and fish. It is probably one of 
those “facultative” parasites, which are not very fastidious as to host, 
and which may therefore find opportunity to develop in a great variety 
of situations. 
1 M. AlexeieS informs me that he found it abundant on one occasion in a larva from 
the neighbourhood of Paris. 
