358 THE MECHANICAL FUNCTIONS. 



those that are destitute of either tusk, proboscis, or nasal 

 horn. 



The most remarkable genus of this family is the Elephant, 

 the colossal giant of quadrupeds. The many peculiarities that 

 are observable in the conformation of this animal have all an 

 obvious relation to the circumstances of its condition. Formed 

 for feeding on a great variety of vegetable substances, and 

 more especially on the tender shoots of trees, fruits, and grains, 

 as well as on herbage, and succulent roots, its organs of mas- 

 tication are powerful, and its teeth of great size. The whole 

 of this apparatus requires an immense development of bone 

 to render it efficient ; so that the head, with its huge tusks 

 and grinders, is of enormous weight. Had this ponderous head 

 been suspended at the end of a neck of such length as to ad- 

 mit of its being carried to the ground, as is the case in grazing 

 animals, it would have destroyed the balance of the body, 

 and would have required greater force to raise and retain it 

 in a horizontal position than was competent to any degree of 

 muscular power. Nature has accordingly abandoned this 

 form of structure, and has at once curtailed the neck, bring- 

 ing the head close to the trunk of the body, and supporting it 

 by means of short, but powerful muscles, which are not im- 

 planted in any particular point of the skull, as they are in 

 other quadrupeds, where the occipital bone forms a crest or 

 ridge for that purpose ; but the general surface of the cranium 

 has been enlarged by an immense expansion given to its inte- 

 rior cellular structure, and, thus, the muscles are attached to 

 a considerable extent of bone, instead of being affixed to a 

 single process, which would have incurred great risk of being 

 broken off by their action. These large cells are constructed 

 with a view to combine strength with lightness ; the plates 

 which form their sides being disposed, in a radiated manner, 

 towards the circumference, and arranged with great regulari- 

 ty ; and the cells themselves, instead of containing marrow, are 

 filled with air, by means of communications with the Eusta- 

 chian tubes, which open into the nostrils : thus, a great extent 

 of surface is given to the skull, without any addition to its 



