198 
HISTOLOGY OF ANIMALS. 
but the discovery of its real seat will, it is to be hoped, 
lead to such a mode of treatment as may be beneficial 
to the two afflicted survivors. 
Fatty degeneration of voluntary muscle is very com- 
mon among the lower animals. All are aware, no 
doubt, of the difference in colour between the flesh of 
the breast of a Fowl and that of its legs, the former 
being more or less white, the latter of a reddish hue. 
If that from the breast be examined, traces of fatty 
degeneration are very apparent in the fasciculi, arising, 
no doubt, from the want of use of the muscle in the act 
of flying. The muscular structure of the legs, on the 
contrary, which are always in exercise, is perfectly 
healthy. I have detected the same disease in the 
muscles of the legs of the Ostriches kept for a long 
time in the Zoological Gardens. These from want of 
use, are perceptibly whiter than those employed merely 
in the support of the body, and also exhibit a consider- 
able amount of fatty degeneration. The same disease I 
have also found in their bones; and it is a fact well 
known to the keepers, that when they once take to 
lying down, their doom may be said to be sealed. A 
knowledge of this circumstance may perhaps lead to the 
more successful preservation of these gigantic members 
of the feathered tribe. In the Sheep many instances 
are on record in which almost the entire muscular 
substance of the trunk has been converted into adipose 
tissue. In the Pathological Series is a mutton chop. 
Prep. 10, nearly all the muscular substance of which 
