400 OBSERVATIONS ON PORRIGO OR TINEA. 
aspergillus parasite, as here delineated, is the next thing to 
being complete. 
It would account for a good many outbreaks of ringworm 
if the aspergillus and tinea parasites turned out to be identical. 
But I must pass on to notice that— 
Third, the identity of the parasites present in the several 
varieties of tinea may be indirectly proved by an examination 
of the various seats or nidi where they are found vegetating. 
From observations made on the subject of the experiments 
above detailed, I have come to the conclusion that the ex¬ 
ternal symptoms presented in all the varieties of tinea, how¬ 
ever conflicting, depend entirely on the particular part of 
the integument, and the constitution and species of the 
patient, in which the disease (parasitical) has established 
itself. 
Favus is almost invariably deepseated, the dermis, epi¬ 
dermis, and hair radicle becoming alike infested. Scutulatus 
or ringworm is in general more superficial, mostly confining 
itself to the hair follicle, hair, and epidermis. Decalvans 
almost restricts its attack to the hair alone, hence the want 
in a great measure of the usual apppearance of epidermic 
disturbance. 
It may, therefore, be set down as a rule that in accord¬ 
ance with the seat of the disease will the external symptoms be. 
These deductions are quite compatible with what we know 
of the habits of other members of the fungus family. For 
example, let us take the common edible mushroom (.Agaricus 
campestris ), and we will find that it assumes an immense 
variety of shapes, and sizes, and appearances; more than 
this, however, we find that although in most situations and 
soils it is safely edible, yet when found in low-lying, secluded, 
unhealthy places, or near stagnant pools, it becomes virulently 
poisonous. The situation changes the nature and quality 
of the A. campestris , and in like manner the shape and 
colour of the tinea parasitical fungus and its effects. 
But, as I find the subject is as inexhaustible as it is inter¬ 
esting, I must conclude my remarks, and let some one else 
with more time and ability resume its consideration. I have 
simply given my own experience and consequent ideas, and 
must just leave them to speak for what they are worth. 
