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2. ON THE BLOOD-COLOURED EXUDATION FROM THE SKIN OF 
THE Hippopotamus. By Joun Tomes, F.R.S., SuRGEON- 
DENTIST TO THE MtppLESEX HosPITAt. 
(Mammalia, Pl. XXI.) 
The Honourable C. A. Murray, in a letter which he addressed 
from his residence at Cairo to Mr. Mitchell, states that the skin of 
the young Hippopotamus entrusted to his care was at times covered 
with a blood-coloured exudation, and that it was most abundant 
immediately after the animal had left his bath. At first this peculiar 
condition excited considerable alarm, but its constant recurrence, and 
the otherwise perfectly healthy appearance of the animal, induced the 
belief that the secretion was normal, or at all events portended no harm. - 
Tn a letter received at a later date than the one I have referred to, 
Mr. Murray says that the exudation, though ‘still preserving the 
same peculiar characters, has diminished both in amount and in in- 
tensity of colour. 
On the day after the Hippopotamus arrived in the Zoological 
Gardens, I had a favourable opportunity of examining the general 
appearance of the skin. The upper surface of the body is dotted 
over with a number of deep brown spots, disposed on a comparatively 
faint brownish black ground. The spots are much more apparent 
when the skin is wet, than when it has become dry from exposure to 
the air. Immediately after leaving the bath, each of the deep brown 
spots may be seen to have a slightly raised centre, from which is 
poured a drop of pink fluid of the consistence of white of egg. This 
peculiar exudation speedily diffuses itself over the surface of the skin, 
and dries with a slightly glazed surface. 
The Arab keeper who attended the Hippopotamus in his passage 
to this country, and who still has charge of him, says that he has 
never seen the red fluid exude, excepting immediately after the animal 
has left his bath ; that it quickly dries up, and does not reappear till 
the animal again emerges from his bath. The end of the nose is how- 
ever constantly a little damp, from the presence of a small quantity 
of a colourless mucous fluid, which escapes from minute pores situated 
' in this part. At the line of junction with the skin and the smooth 
semi-mucous membrane which covers the extremity of the nose, the 
fluid has a faint pink colour. 
On the second day of the animal’s residence in the Gardens, I col- 
lected a small portion of the coloured fluid from the middle part of 
the back, and after securing it between two slips of glass, placed it 
in the field of my microscope, which I had conveyed there for the 
purpose of making an examination previous to the fluid undergoing 
any change, either from decomposition or evaporation, which a slight 
lapse of time might possibly have affected. 
The following particulars were obtained from the examination I 
then made:—The exudation is composed of a transparent fluid in 
which float two kinds of corpuscles ; one kind is tolerably abundant, 
and is both transparent and colourless; the other is comparatively 
rare and of a bright red colour. To the solution of these latter 
bodies the fluid owes its peculiar colour. 
