2 VETERINARY PARASITOLOGY 
to much-branched filaments, known as “ hyphe.” 
These intermingle and produce a matted mass, which 
is known as a ‘“‘ mycelium.” Besides these, there are 
other branches given off, usually at right angles, which 
have a reproductive function, and which bear at their 
extremity spore-cases known as “sporangia.” Each 
sporangium contains a large number of minute spores. 
In some cases the spore-case contains only one spore, 
and is then known as a “‘ conidium.”’ 
A modified form of sexual reproduction is seen in the 
Ascomycetes, in addition to the ordinary asexual repro- 
duction. Two hyphe come together, and a process 
takes place known as conjugation, and results in spore 
formation afterwards. The spore-case is known as an 
“ascus,” and contains eight spores, four of which would 
be seen in a longitudinal section and two in a transverse 
section. 
There are three chief species of skin fungus seen in 
our domesticated animals. These are, respectively, Tri- 
chophyton, Microsporon, and Achorion. 
1. Trichophyton.—The mycelium consists of fine elon- 
gated tubes, showing a single contour. They may be 
simple, segmented, or dichotomously branched. The 
hyphz twine round the hairs, forming a whitish mass 
at the roots, and also penetrate into the interior. The 
result is that the hairs become rough, often split, and 
finally fall out or are cut across. 
The spores are spherical or elliptical, and are con- 
tained inside the older segments, which they almost 
entirely fill. They are so numerous as to form a chain, 
and often obscure the hyphz themselves, when a scraping 
is examined microscopically. 
On agar-agar Trichophyton develop a green culture. 
The skin fungi will grow on most media, providing a 
little glucose is added. Both this variety and Achorion 
liquefy gelatine. 
