PARASITOLOGY. 65 
Sulphur is not essential when nicotine is used. The 
nicotine must be at least .07%. 
DEMODECIDAE. 
The sub-family Bemodecidae includes a group of 
parasites that live in the hair and sebaceous follicles 
of the skin and produce cuticular pustules. They are 
placed under one genus,—Demodex (worm-like) and 
one species,—Folliculorum (follicle). 
General Description.—Under a low-power micro- 
scope the parasite has a general outline similar in 
shape to an oat grain. The head part is broad and 
is provided with a stylet or lancet-piece arranged at 
the anterior extremity. The thorax is not distinctly 
separated fromthe abdomen. The larva is provided 
with three pair of legs, the adult with four. Each 
leg is made up of three short segments, the last 
one being very short and provided with two hooklets 
or claws. 
Lite History.—The life history is similar to that of 
the sub-family Sarcoptidae. The ova are laid in the 
pustule. The newly hatched larvae are asexual and 
are provided with three pair of legs which are mere 
tubercles. After moulting the larvae are observed 
