126 
HISTOLOGY OF ANIMALS. 
ligament was upwards of 8lbs, and the striped fibres are 
most abundant on the outer surface, the interior being 
occupied by plain fibres alone. The striped fibres are 
not confined to the Giraffe , I have lately seen them in 
the Rhinoceros , the Sheep, and even in arteries. 
A modification of the yellow fibrous element consti- 
tutes the elastic coat of arteries ; which is well shown 
in a fine specimen taken from the aorta of a Whale 
upwards of 50 feet in length ; the diameter of the 
vessel is about 12 inches, and the thickness of the 
elastic coat 1^ inch. When examined by the micro- 
scope, the fibres of arteries exhibit all the characters 
of those of ordinary elastic tissue, except that they are 
much more minute and less easy of separation. 
Another variety of elastic tissue occurs in the liga- 
ment supporting the expanded wings of all our larger 
birds, such as the Ragle , Crane , Heron, &c. The 
ligament from the Ragle is quite as elastic as caout- 
chouc. 
The last variety of this tissue which I shall notice, is 
that situated between the valves of Conchiferous Mol- 
lusca , in which it performs the office of opening the 
valves whenever the adductor muscle ceases to contract. 
In some shells, as the Oyster, this elastic substance is 
placed within the hinge, in others, as the Cockle, it is 
external to it ; in the former, the expansive power of the 
compressed substance separates the valves, but in the 
latter, the same object is gained by the contraction of 
the hinge ligament. The structure of this form of 
