12 
Hogg, on Vegetable Parasites. 
briefly into the early history of the parasitic diseases, and 
their recognised division into species. 
It is now more than a quarter of a century since Bassi, of 
Milan, discovered the vegetable character of a disease which 
caused great devastation among silkw^orms ; and, about the 
same time, Schonlein, of Berlin, was led to the detection of 
certain cryptogamic vegetable formations in connection 
with skin diseases. The observations of this distinguished 
man have been abundantly confirmed by Gruby, Bemak, 
Bobin, Kiichenmeister, Bennett, Jenner, and others, most 
of whom attempted to identify the fungus with the disease 
which they believed to be produced by it, and in this way 
separate and detach some of the most common skin diseases 
from the rest, and so regard them simply and almost exclu- 
sively as fungoid or parasitic diseases. Thus, the parasite 
supposed to be peculiar to, and productive of, each disease 
has been minutely described, and honoured with a name 
derived from the name of the disease which it is supposed to 
have originated, as appears in the following table : 
WiLLAN. 
Bazin. 
Wilson. 
Pakasite. 
Porrigo favosa and 
lupinosa 
Porrigo scutulata 
Porrigo decalvans 
Mentagra 
Pityriasis versicolor 
Tinea favosa 
Tinea tonsurans 
Tinea decalvans 
Tinea sycosa 
Pityriasis 
Favus 
Trichosis fur- 
furacea 
Alopecia 
Sycosis 
Chloasma 
Achorion Schonleinii. 
Tricoyhyton tonsurans. 
Mierosporon Audouini. 
Microsporon mentagra- 
phytes. 
Microsporon f urf ur. 
Now, this very tempting theory involves an important 
principle of pathology, inasmuch as it places the parasitic 
fungi above described in a category by themselves, and in- 
vests them with characteristics entirely at variance with 
those of the natural history of the family of fungi, whose 
leading feature appears to me to be that of selecting diseased 
and decayed structure as the soil most essential to their 
existence; whereas this hypothesis assigns to them healthy 
organized matter to live and prey upon, and thereby esta- 
blishing specific diseases. In examining into the truth or 
fallacy of this theory by the light of physiology, we must 
bear in mind that the surface of the human body is supplied 
with a delicate covering, one office of which is to excrete, 
and another to eliminate or exude, effete matter from the 
