MEDICAL MICROSCOPICAL SOCIETY. 407 
sions and not their cause, but due to over-distension of the vessels 
during hyperemia of the cord, and drew attention to the similarity 
of the appearances now seen, to those described by Dr. Dickenson 
in cases of diabetes. 
Mr. Needham has observed the same changes in the brain in cases 
of hydrophobia, and in cases of heart disease where there had been 
much congestion. 
The President thought the changes described not uncommon ; 
they were mentioned long ago by Durand-Fardel, as owing to 
wasting of the brain in old age, and lately by Dr. Lockhart Clarke 
in paralysis of the insane. These appearances may not be patho- 
gnomic, and Dr. Dickinson could not find them in the parts of the 
brain which when injured cause diabetic condition ; they are found 
too in seemingly healthy brains. His first described the perivas- 
cular spaces, and by some they are considered lymphatic, but the 
name is usually given to the tunica adventitia of the artery sepa- 
rated, and under diseased conditions filled with blood or inflam- 
matory material. In the case given it was not likely the spaces were 
owing to simple mechanical distension of the vessel, for if so, why 
should the vessel not remain distended? it would scarcely again 
collapse. They were more easily explained by wasting of the brain 
substance, and consequent filling of the perivascular spaces— 
whether tunica adventitia or not—with serum, since a vacuum 
cannot exist, and this wasting, a severe illness, or bad feeding 
might bring about. 
Dr. Greenfield had always observed a catarrhal condition of the 
central canal of the cord in cases of convulsions; and what the 
President described as tunica adventitia, he thought an additional 
structure to help support the vessel. 
Dr. Coupland, in reply, stated he had in preparing the spinal 
cord preserved it first for twenty-four hours in spirit and water, and 
then in weak chromic acid. He did not know if the child were 
badly nourished, nor how long it had been ill. 
Urate of Soda in the Heart.—Mr. Ward exhibited a specimen 
where, in a gouty subject, the coronary artery was found plugged, 
the plug containing acicular crystals of urate of soda. Death was 
sudden, from rupture of left ventricle; the heart substance was 
friable. 
The President had seen sudden death in cases of plugging of the 
coronary artery. 
Dr. Greenfield stated that fatty change in the heart was said to 
follow plugging of the coronary arteries—he had not observed it 
uniformly. He quoted Dr, Quain’s cases of plugged coronary artery ; 
in all death was from ruptured heart. 
Mr. Golding Bird asked if any chemical test had been applied 
to the crystals. He had once succeeded in obtaining under the 
microscope, by the addition of weak acid, crystals of uric acid, from 
the acicular crystals of urate of soda contained in a section of 
“gouty”’ cartilage. 
Mr. Ward, in reply, had not applied any chemical test; the heart 
