382 ANATOMY. 



cavity of the pelvis not at all diminished : both could not have been 

 done in any other way. 



The canal of, the spine is largest in the neck and loins 1 . This 

 answers two purposes ; first, it allows a greater motion in those parts 

 without the medulla being hurt ; secondly, it makes the parts stronger 

 with the same quantity of matter: this is most remarkable in the 

 loins. 



In man the crooks of the spine vary in different parts, at different 

 ages, of the same person. In the child it is most in the back, and 

 is backward ; owing, perhaps, to the weight of head ; in the adult it is 

 as much in the loins and is forward. This, perhaps, is owing to the 

 weight of the thorax and head, and the loins being the most moveable 

 part. 



The ligaments between the vertebrae are stronger externally in pro- 

 portion as they are removed from the centre of motion. 



The trunk is made up of three parts, the head, thorax, and pelvis — 

 all at a distance from one another ; and this is common to all qua- 

 drupeds. It was necessary that these parts should have motion ; there- 

 fore they are placed at some distance from one another, which makes 

 the necessity for the neck and the loins. 



The back-bones of animals differ very much respecting motion, and 

 especially the degree of curving; they might be divided into the 

 straight and curved. Horses, elephants, rhinoceroses, and ruminating 

 quadrupeds, which only stand or lie, have spines of the straight kind. 

 However, there is a gradation between the straight and the curved 

 spine. The curved or bendible spine belongs to those animals which 

 can sit, either iipright as in man, or bowed forward; the monkey, 

 dog, &c. forming the gradation between the one and the other. 



Animals that have very long bodies, and are small 2 , generally have 

 their backs bent upwards, archways : the use of this must be to sup- 

 port the body as an arch is supported. 



In quadrupeds and birds the ilium is a long bone, situated nearly at 

 right angles with the thigh-bone, crossing its head like the upper part 

 of the letter T ; giving origin, along its whole sweep, but principally at 

 its ends, to muscles which flex and extend the thigh-bone. The middle 

 part of the ilium is so near the joint as to give but a small surface for 



1 [ Vide Mr. Henry Earle's paper thirty years after Mr. Hunter's death, for this 

 single fact, Phil. Trans. 1822 or 1823.— W. C. Mr. Earle also regarded the ex- 

 pansion at the two ends of the neural canal in the neck -vertebra of birds as an im- 

 portant element of his paper. — E. O.] 



2 [See the skeleton of the marten [Mustela Martes], No. 4152, and that of the 

 sable \_Mustela zibellina], No. 4168, Hunterian Osteol. Series.] 



