THE ANTLERS. 177 



tween the old and the new bone, for the internal supply of nutri- 

 ment. 



But this is not all. Copious as is the supply of blood which 

 these great arteries are capable of furnishing, still it is inad- 

 equate for so rapid a growth ; so we find another set of blood- 

 vessels, communicating directly between the persistent and the 

 deciduous osseous formations. These pass up through the body 

 of the pedicel into the antler, and together Avith those just de- 

 scribed, perform the office of the medullary artery in the internal 

 long bones, supplying it with nutriment internally, and commu- 

 nicating, as in the case of common bones, with the Haversian 

 systems connected with the periosteum. Let us examine a cross 

 section of the pedicel, just below the seat of the antler, when the 

 antler is but half grown and the work is going on in its full 

 vigor, and we find it open and spongy, apparently composed of 

 pretty compact cancellous tissue towards the circumference, but 

 with open canals near the middle. In the specimen now before 

 me, which is cut across, one of these canals is nearly one line in 

 diameter. This is the largest distinct canal for the passage of 

 an artery through the pedicel which I have found, but when these 

 canals are smaller, there are more of them, if examined at the 

 same stage of growth. These canals afford abundant passage for 

 the blood-vessels passing up through it into the new-growing 

 antler. 



Let us compare it with another, also on my table, on which 

 the antler had become hard, and was nearly readj^ to be cast 

 off. Now we find this pedicel, which a few months before was 

 so porous, has become a compact bone throughout, with the cav- 

 ities so far filled up as to collapse the blood-vessels and obstruct 

 the appreciable passage of the red blood, though, of course, the 

 laeuuEB and the canaliculi are still preserved as necessary to its 

 own continued vitality ; but all the visible canals ai'e now filled 

 up. Here, then, is an order of nature found nowhere else, be- 

 cause the necessities of the case nowhere else require it. We 

 find a persistent bone, alternately compact and porous, alter- 

 nating annually, simply because it is necessary to the per- 

 formance of a peculiar function, nowhere else in the whole 

 range of nature's works demanded. 



When the time approaches for the new antler to commence its 

 growth, the laminae which had filled up the canals in the pedicel 

 through which the nutriment to promote that new growth is to 

 pass, are absorbed away and the canals are thus enlarged, and 



12 



