72 THE HOUSE FLY—DISEASE CARRIER 
also been given the specific name Muscat domesticat by 
H. Werner. 
Nematode Parasites of the Typhoid Fly 
The nematodes, or thread-worms, have long been 
subjects of observation. They are greatly elongated, 
thread-like organisms, frequently of considerable size; 
for the most part laying eggs, but in rare cases bearing 
living young. The younger stages or larvae of most 
of them have a different habitat from that of the adult 
worm. Some of them develop in damp, muddy earth, 
migrating finally to lead a parasitic life within some 
animal; some are parasitic in plants. The old time super¬ 
stition that a horse-hair when left in water for a suffi¬ 
cient length of time becomes a living worm arises from 
observations upon some of the largest nematodes. Very 
many insects are parasitized by the worms of this group. 
H. J. Carter, in Bombay, in November, 1859, while 
examining the head of a common house fly, noticed 
that two nematode worms came out of it. Later, in 
July, i860, he discovered that on the average about 
every third fly in Bombay contained from two to 
twenty or more of these worms, which were chiefly 
to be found in the proboscis, though occasionally oc¬ 
curring among the soft tissues of the head and hinder 
part of the abdomen. He described them as bisexual, 
mature, and nearly all of the same size. He placed 
them in the genus Filaria, and described them as Filaria 
tnuscce in the Annals and Magazine of Natural History, 
Vol. VII, pages 30-31. 
