CHAPTER I 
PARASITES AFFECTING THE SKIN 
VEGETABLE PARASITES 
RINGWORM 
THE vegetable parasites affecting the skin of animals are 
a series of very low forms of plant-life, and are usually 
classed with the moulds. The skin diseases they produce 
are grouped together under the term “ ringworm,” but 
are caused by variations of the same fungus. The 
differentiation between them is only marked as regards 
their mode of reproduction, though each shows a prefer- 
ence for some particular culture medium. They are all 
parasitic fungi, and chiefly attack the epidermis, at the 
expense of which they maintain their existence. Several 
observers have stated that they are capable of sapro- 
phytic existence, quite apart from an animal host, and 
thus infection may take place without any direct con- 
nection with an affected animal. It is certain that their 
vitality is exceedingly great, and-they show a marked 
resistance to desiccation, and various experimenters 
have found that scabs or crusts will remain active and 
produce ringworm in an animal after having been re- 
moved from another animal for a period of from one to 
two years, 
The common mode of reproduction among the skin 
fungi is asexual, by sporulation. The spores give rise 
I 
