CHOROID PLEXUSES OF THE HORSE. 149 
The author is unacquainted with any crystalline form of fat to 
which these bear a resemblance. Neither the alcoholic nor 
eethereal solution yielded any tubular crystals.” The lameliated, 
lanceolar objects thus described appear similar to those I have 
witnessed, although the drawings given of them are not exactly 
identical; they vary in my objects, apparently being narrower, 
and not so bent. However, these are a few selected from 
many, and when examined with a higher power no appreciable 
difference can be detected. I venture to infer, that, had Mr. 
Muller tested the objects further, he would, in like manner, have 
found them to consist of modified scales of cholesterin. 
The envelope of the tumours consists in condensed areolar 
tissue, interspersed with fat and earthy matter; the latter par¬ 
tially effervesces if dissolved in acid. There are no distinct 
globular phosphatic bodies. The bulk of the adventitious 
products consists of cholesterin and irregular earthy masses. 
Mr. Roscoe, on testing them, for which I wish publicly to 
acknowledge my gratefulness, re-assured himself of the presence 
of “ lime and phosphoric acid.” He finds “ also that an effer¬ 
vescence occurs in dissolving the substance in hydrochloric acid, 
which is no doubt due to the presence of carbonic acid. 
Magnesia does not occur in the deposit. There appears to be 
also an organic acid insoluble in ether.” 
I have had occasion to examine other two tumours from a 
horse’s brain of most extraordinary size. The one is two inches 
and a quarter long, by one and three-fourths broad; the other 
is two and one-third by one and a third inches. These filled 
up the whole cavity of the ventricle, having led to the ab¬ 
sorption, on either side, of the intraventricular portion of the 
corpus striatum, taenia semicircularis, anterior part of the optic 
thalamus, and hippocampus. No history is appended to the 
case; and whilst I have not yet been able to acquaint myself 
thoroughly with the nature of the masses, they appear, in many 
respects, similar to the others, only varying in the amount of 
cholesterin, which is so excessive and so peculiarly arranged as 
to admit of their classification under the head of cholestro- 
tomatous tumours, so rarely met with. More may, perhaps, be 
said respecting these and other such cases v T hen time and 
circumstances permit. I wish only to add, that Dr. Jenner 
has in his possession two choroid plexuses enlarged similarly 
to Mr. Percivall’s: strange to say, the woman from whom they 
were removed had no symptoms before death which would 
have led to the inference that her brain was the seat of disease. 
In apparently healthy choroid plexuses from two human adults, 
I have found the phosphatic bodies with a concentrically ar¬ 
ranged fibrous basis, but no cholesterin. 
VOL. XXV. X 
