PATHOLOGY OF STRINGHALT. 
135 
reference to the experimental physiologist, and as to the 
results which would be produced by the experiments he sug¬ 
gests on the nerves. There can be no doubt that the 
irritated nerves excite the muscles. That, however, is not 
the point between us, but whether the cause of irritation has 
its origin in the hock or the spine, or anywhere between 
those two points. 
In reference to the two cases of spavin, followed by string- 
halt, referred to by the professor, I would ask if ulceration 
of the astragalus may not have existed at the same time ? 
The professor says, “ I have dissected many ulcerated hocks, 
but I am not aware that stringhalt could be traced, in any 
one instance, to disease of this nature.” Has Professor 
Varnell made post-mortems on horses known to have had 
stringhalt without finding ulceration of the astragalus ? 
Again, he says, “let us see whether that which Dr. 
Busteed describes as an ulcer is in reality one.” “ If 
such ulcers as the doctor describes had really existed, 
would not the synovia he so frequently alludes to have 
been discoloured ? ” That would depend on the extent 
to which the bone was diseased; if but slightly affected, I 
think there would be no discoloration ; I did not, however, 
submit it to microscopic test. 
Professor Yarnell further asks, “If the depressions the 
doctor met with on the articular surface of the astragalus, 
and occasionally on the tibia also, are not true ulcers, what 
are they?” He answers this question himself by observing, 
“ Why, simply those parts of the articulations upon which car¬ 
tilage was never developed. They were, I have no doubt, con¬ 
genital.” I must confess I am at a loss to understand the 
professor. Does he mean that bone is to be found in the 
articulations of the colt at birth ? or does he mean that foals 
are liable at birth to a particular form of ulceration ? If so, 
I think, in all fairness, he ought to have described the appear¬ 
ance between congenital ulceration or defect, and ulceration 
arising from injury or disease, so as to enable me to judge of 
the difference between ulceration in man (with which I am 
familiar) and that of animals, as they appear to me to be alike. 
Again, he remarks, “ I believe this form of disease sometimes 
suddenly assumes a different character, when the undermined 
articular parts of the bone and its much-thinned cartilage 
caves in. But this is not the so-called ulcer of Dr. Busteed.” 
In Case No. 3 I say, “ the astragalus had in it a deep ulcer, 
which had penetrated the substance of the bone;” this is the 
ulcer of Dr. Busteed, but not in such an exaggerated form as 
described by Professor Yarnell, 
