396 OBSERVATIONS ON PORRIGO OR TINEA. 
spores of the fungus of favus will not under any circum¬ 
stances produce T. scutulata, nor, vice versa, will the spores 
of T. scutulata in any case produce favus. 
The fungus Achorion Schcenleinvi is said to be restricted to 
favus; while T. scutulata is caused by the Tricophyton 
fungus, and T. decalvans by the fungus Microsporon Au~ 
douini. 
On the other hand, several medical authorities of un¬ 
questionable ability, such as Dr. Tilbury Fox (in his tf Skin 
Diseases of Parasitic Origin’), and Mr. Jabez Hogg (in the 
f Quarterly Journal of Microscopical Science,’ January, 
1866), as well as several continental investigators, maintain 
that all the varieties of this vegeto-parasitical skin affection, 
however glaringly dissimilar their external appearances may 
be, are caused by the presence of one and the same parasitical 
fungus. 
It were needless to deny, for instance, that the outward, 
symptoms seen respectively in a case of favus and a case of 
T. decalvans are extremely conflicting. Still, if we bring the 
microscope to bear on the subject, little or any apparent, and 
I think no actual, difference will be found in the character 
and arrangement of the spores, sporophorous tubes, and 
mycelium composing the parasitical fungi present in the two 
varieties of the affection mentioned. 
The real cause of the varied appearances presented by the 
action of the fungus in the several forms of this affection 
must be looked for in the soil, so to speak, in which it is 
found vegetating, and also in the particular part of said soil 
(the skin and its appendages) in which its various phases are 
observed. It may be superficial, deep seated, or entirely 
capillo-follicular. 
Since my previous communication I have conducted a 
series of four experiments in order to test the results of trans¬ 
mitting the contagious material of common ringworm in 
cattle to cats, rabbits, and pigs ; being fully convinced that 
T. favosa often follows upon its transmission to man, I con¬ 
cluded that I ought to find corroborative evidence in its 
effects on these smaller animals. The following details will 
show whether my conjectures were correct or otherwise. 
First experiment .—Having with a scissors removed the 
hair from a small spot on the head of a young white rabbit, 
I moistened the bare spot with a little spittle, and then well 
rubbed upon it a small quantity of contagious powder or dust 
scraped from crusts on the head of a yearling quey suffering 
from common ringworm, or T. scutulata . The crusts on this 
quey were of the usual dirty whitish-grey colour. On ex- 
