THE BONES OP THE HEAD. 29T 



whereby they are furnished with their vessels. The shape of 

 particular bones intimately corresponds to the purpose for 

 which th6y are intended ; where for the office of protection 

 we find them flat, and where for the purpose of motion, long 

 and cylindrical, as in the extremities. 



THE BONES OF THE HEAD. 



In the construction of the skull the most perfect mechan- 

 ism is displayed. The first object to be obtained is the pro- 

 tection of the brain from the accidents to which, from the 

 pepuliarities of animals, it is mostly exposed. For this pur- 

 pose the skull consists of two tables or plates ; the outer 

 thick and tough, the inner hard and brittle :_ the former, by 

 yielding in a measure to resistance, diminishes concussion, 

 whilst the latter, by its hardness, prevents sharp bodies from 

 penetrating to the brain. Now, if these two plates were re- 

 versed, the brittle would not only be in great danger of frac- 

 ture, but would also vibrate considerably ; and the injurious 

 effect of this vibration may well he conceived when we are 

 told that, even with the present wise precaution, it often oc- 

 casions in the human subject greater mischief than the most 

 serious fractures. 



There is a remarkable difference in the appearance of the 

 head in the horned and the polled sheep ; the former have a 

 more pugnacious, and it may be a more sensible appearance, 

 owing to the elevation and projection of the upper part of the 

 head. This, however, is in appearance only, for the promi- 

 nence of the head is not formed by any increase in the brain, 

 but is owing to the considerable space which exists between 

 the two tables of the skull, the outer being half an inch or 

 upwards fr6m the inner. This separation accomplishes two 

 purposes, one being the additional security it affords to the 

 brain by the interposition of this vacant space, and the other 

 the greater root or basis^t affords to the horns. And when 

 we consider that horned sheep are generally more pugnacious 

 than others, and that they have not only the will, but the 

 power, of butting each other with great force, the additional 

 security is not without use. In fact the brain is seated so 

 much beneath and behind the forehead, that very little of the 

 shock can be communicated to it. This circumstance too 

 operates in affording protection to the polled sheep as well. 

 Between the skull and the brain are interposed, several mem- 

 branes, which also assist materially in preventing vibration, 



