Home on Comparative Anatomy. 135 



engaged to fill up this chasm, for which much labour and inquiry 

 would be requisite. Upon the present occasion, therefore, we shall 

 consider it our first duty and main object, to point out and discuss 

 that which peculiarly belongs to Sir Everard Home, canvassing those 

 views and opinions which are indisputably his own, and endeavouring 

 to appreciate the originality and merit of his discoveries. 



The statements respecting the powers of motion in vegetables, as 

 well as many ingenious remarks upon the minute structure of muscle 

 and its combination with elasticity, are, we presume, to be ascribed 

 to Mr. Hunter, but the discovery of the structure of the left ventricle 

 of the heart, is due to our author; at least he made it known in the 

 year 1790, and it has never been claimed by any other anatomist, 

 but acknowledged as correct, and taught in our Schools since that 

 time : it is one of the most beautiful mechanical arrangements of the 

 animal frame, and we cannot better communicate it to our readers 

 than in the author's words. 



" The muscular structure of the left ventricle of the human heart, 

 detached from the other parts, is an oviform hollow muscle, but more 

 pointed at its apex than the small end of a common egg ; it is made 

 up of two distinct sets of fibres lying upon each other. Those which 

 compose the outer set have their origin around the root of the aorta, 

 and in a spiral manner surround the ventricle to its point, where 

 they terminate, after having made a close half turn." 



" The fibres of the inner set ate similar in their mode of surround- 

 ing the cavity, and in their termination, but they decussate the other 

 set through their whole course, and the two sets are blended together 

 where they terminate." 



" In this muscle the fibres, by their spiral direction, are nearly one 

 fourth part longer than the distance between their origin and ter- 

 mination, and the two sets acting in different directions, one half less 

 contraction is necessary in each fibre than would otherwise have 

 been the case ; while the turn both sets make at the apex, fixes it 

 and prevents lateral motion. 



On the growth of shell and of bone there is nothing deserving of 

 particular notice, but the formation of the intervertebral joints in 

 fishes is curious as baffling artificial imitation. The illustration of 

 this subject is taken from the Squalus Maximus, and it appears that 

 each joint is a cavity filled with a fluid and forming a kind of ball 

 and socket. 



The subject of progressive motion, commenced in the first, is con- 

 tinued in the third volume, and is extremely interesting in its details 

 and illustrations. The observations on the feet of the fly and other 

 animals that walk against gravity, we believe are original and due 

 to our author ; they are illustrated by excellent engravings from Mr. 

 Bauer's pencil, from which it appears that the animal is supported 

 by a mechanism resembling cupping glasses. It is curious that the 

 hind feet of that enormous animal the Walrus, are constructed upon 



