IIUMINATING ANIMALS. 
91 
This is of a cellular structure in its interior, and in- 
dependent of its general use to retain water alone, 
it appears that longer deprivation from liquid enables 
the animal to dilate the cells, and renders the com- 
partment capable of containing a greater quantity of 
its invaluable store. 
The horns, the hoofs, and hair, present peculia- 
rities in the ruminating animals. The horns in 
many of the species, particularly in the deer of 
temperate climates, are deciduous annually ; and 
when the nourishing vessels, as it were, become ob- 
literated by their growth, they lose their vitality, and 
fall olF, to give way for the reproduction of the new 
material, which commences about the period when the 
system becomes influenced by the desires of rutting. 
In these animals, it springs from, and is for the time 
attached to, the prolongation of the’ frontal bone, 
which serves as a base or root ; and when in its per- 
fect state, or when the complete obliteration of the 
nourisliing arteries takes place, it is of the consist- 
ence of bone, and remarkably compact and hard, en- 
tirely different in composition from the substance of 
true hoin, as seen among the Bovidm or Oxen, &c. 
bir Everard Home looks upon their consistence as 
similar to bone, and thus describes their fonnetion : 
“ Besides the common bones of an animal body, 
there are othei's peculiar to particular animals, which 
only last for a season. Of this kind are the bony 
projections or horns on the skull of the deer, pecu- 
liar to the male. As these are of quick growth, and 
