TUMOURS IN THE BRAIN. 
1 G5 
occupied all the anterior part of the ventricle, and was of an 
ovoid form. Its largest diameter measured *050 of a milli- 
metre, and its smallest, -020. 
The largest diameter of the left plexus was only 0 35 of a 
millimetre, and the smallest, *01 6. These plexuses were, 
therefore, from 15 to 20 times larger than in their normal 
state. Their surface was uneven ; their substance firm, and 
of a deep red colour, slightly tinged with violet. Each tu- 
mour contained a considerable quantity of small nacreous 
bodies, which are known to be composed principally of 
cholesterine. 
The cerebral substance, upon the whole, was of its usual 
consistency and density. It was of a slight yellow colour, 
however, in the parts contiguous to the enlarged plexuses, 
where it was also very much indented by the impressions 
which had been made upon it by these bodies. The plexus 
of the fourth ventricle was very red, and the pituitary body 
was also enlarged. M. Faivre, who assisted me in the au- 
topsy of the horse, has very carefully examined with the 
microscope some portions cut from the left plexus. He found : 
lstly. That the vascular element chiefly prevailed ; the cho- 
roidal villi being closely compressed one against the other. 
‘2dly. That the pavement epithelium was of its normal 
character. 
3dly. That cholesterine was disposed in crystaline plates, 
which were lying one upon the other, similar to the leaves of 
a book. This substance was, he observed, to be encircling 
the arterial bunches, and filling, likewise, the spaces between 
the villi. 
4thly. That some phosphate of lime was deposited in a 
granular form. The serous fluid presented nothing remark- 
able. 
The principal lesions which I have just described, have 
been previously observed by several veterinary surgeons, 
and among others, by MM. Vatel, Renault, Villate, and 
myself. M. Bouley, jun., has likewise some time since de- 
monstrated the existence of pearly masses of cholesterine in 
the tissues of the plexus choroides. 
MM. Vatel, Renault, Villate, myself, and several others 
have observed that an increase of the size of the plexuses, 
together with modifications in the composition and structure 
of these organs, coincided with different functional diseases 
of the brain, and which they had without doubt produced. 
We have remarked, also, that these lesions were accompanied 
with abundant accumulation of serous fluid in the cerebral 
ventricles. One would have thought that similar lesions 
