THE HORSE’S FOOT. 
185 
the nutrition of the horn underwent the same alteration with nu¬ 
trition of hairs in the second affection. 
Megnin in 1864, observed, in operating upon fresh pieces 
taken from the living animal, and from one which had not re¬ 
ceived any treatment, that in canker there is constantly a crypto¬ 
gram, as in favus, and that canker is a parasitic affection. 
Examining the caseous product of the abnormal secretion 
which characterizes canker, Megnin found in it a large quantity 
of very animated vibrios, swimming in a liquid having in suspen¬ 
sion numerous epidermic cells more or less advanced in dissolution ; 
he found besides rounded corpuscles, which he recognized as the 
spores of the cryptogam, and from which the vibrios escaped at 
the maturity of the granulations there contained. In examining 
the fici, he has recognized them to be an aggregate of hypertro¬ 
phied villosities, at the base of which were found in the mass ob¬ 
tained by a slight scraping epidermic cells or parts of cells en¬ 
closed in a net work of inter-crossed, ramified threads, appearing 
to rise from certain centers marked by an agglomeration of spores, 
forming in their whole a yellow spot. In the water of the mi¬ 
croscopic preparations, one finds also, several of these isolated 
threads, epithelial cells, globules of lymph, of blood and finally 
spores ; very rarely vibrios ; oftener micrococci. These threads are 
nothing more than the parasites, the mycelium product of the 
vegetation of the spores; those contained in the serosity, swell, 
break up, and the granulations which escape from them become 
for some time the vibrios, or as we prefer to call them pseudo¬ 
vibrios ; as soon as the brownian motion, which for some time 
animates the granulations, ceases, the cells which have proceeded 
from them (the micrococci) gather together in chains and form 
the characteristic threads of the mycelium. 
This parasite of canker has been named by Megnin the kero- 
phyton or parasitic plant of the horn by analogy with the tricho¬ 
phyton, the parasite of the hair. We consider this name very ap- 
priate and prefer it to the name of oidium batracosis , parasite of 
canker, which Mr. Megnin has also proposed. 
Etiology —The causes of canker are yet but little known ; 
there is one, however, 'which cannot be ignored and which, 
if it does not produce the disease, assists materially in its 
