STEUCTURE, DEVELOPMENT, AND BIONOMICS OE HOUSE-FLY. 379 
their way into the ovaries, where they undergo autogamy 
and infect the subsequent brood. 
In Madras Patton found that 100 per cent, of the flies were 
infected with the flagellate ; Prowazek found it in 8 per cent, 
of the flies at Rovigno. In the cold season in the plains 
(India) Lingard and Jennings (l.c.) found the flagellate in 
less than 1 per cent, of the flies examined ; in the hills 
(Himalayas), at an elevation of 7500 feet, the flagellates were 
most numerous during’ the hottest season of the year, and 
gradually deci-eased in number to October and November, 
when none were discovered. 
One of the chief points of interest in connection with this 
flagellate is its similarity to the “ Leishmann-Donovan ” 
body, the parasite of kala-azar, as it was this resemblance 
that prompted Rogers (1905) to suggest that the latter 
parasite was a Herpetomonas, which I think Patton has 
now conclusively proved to be tlie case, and he calls it 
Herpetomonas donovani (Laveran and Mesnil). 
Crithidia M u sc<e- domes tic ae Werner. 
This pai’asite has been recently described by Werner (1908), 
who found it in the alimentary tracts of four out of eighty-two 
flies. It measures 10-13 /n in length, the length of the body 
being 5-7 jj. and the flagellum 5-6 ju. As in other membei’S 
of the genus Crithidia, which is closely allied to Herpeto- 
monas, the breadth of the body is great compared with the 
length, and the kinetonucleus and trophonucleus are rather 
close together. A short, staining, rod-like body lies between 
the kinetonucleus and the base of the flagellum. The flagellum 
is single. Dividing forms undergoing longitudinal division 
were frecpiently found. The kinetonucleus appears to divide 
first, followed in succession by the flagellum and the tropho- 
nucleus. Forms undergoing division and showing a single 
trophonucleus and double kinetonucleus and flagellum were 
also found. Cases occurred in which the fission began at the 
