230 



ZOOLOGY. 



the frontal bone, resembling what medical men call an exos- 

 tosis, or the callus of fractured bones. These protuberances, 

 which are very compact, grow rapidly, and carry the integu- 

 ments with them; they are also very vascular. After a 



Fig. 176. Head of the Goat. 



Fig. 177. Head of the Eland. 



time, a series of osseous tubercles begin to form around 

 the base of the osseous horn, which increasing, obliterate* the 

 bloodvessels, thus cutting off the supply of blood to the 

 integuments covering the antlers. Tin- integuments drop 

 off consequently, and disappear, leaving the antler itself ex- 

 posed. And now the antler itself dies, as it were necrosed, 

 and ends by being detached from the cranium. In twenty- 

 four hours after this, a thin pellicle covers the surface from 

 which the antler had been detached, and soon a new pro- 

 longation begins to grow in the place of the one which lias 

 been shed. Generally, the new antler is greater than that to 

 which it succeeds, and its branches are larger and more nu- 

 merous ; but it is of no longer duration than the first, and it 

 undergoes the same changes. 



With one exception, the rein-deer, antlers grow only in the 

 male. The phenomenon has obvious sympathies with the 

 organs of reproduction, for they persist lor more than a year 

 in those animals in which the rut does not come to a crisis 

 and is limited. It is periodic, and occurs in the spring. 



394. The exteiiMon of the nose in the elephant into a 

 flexible and dexterous proboscis is a modification of the organ 

 well deserving notice. The proboscis of the elephant is, in 

 fact, an extension of the nostrils, forming a double tube, and 

 fitted to perform the office of a hand and a nose. By it water 

 and food are conveyed to the mouth, and air to the lungs ; 



