344 THE FARMER AT HOME 



all, even the most ingenious and boasted productions of human skill. 

 The difference is recognized at the first glance ; the distance is im- 

 measurable. The springs and wheels of mechanical instruments 

 have no power of repairing themselves, when they are bent, broken 

 worn, or spoiled ; but such a faculty is enjoyed in various degrees by 

 every animal and by every plant. 



At different periods of the year, several organized beings lose, by 

 a spontaneous and natural process, certain parts of their bodies, which 

 are subsequently renewed. Examples of this occur in the fall of the 

 stag's horns ; in the moulting of birds ; in the renewal of the cuticle 

 of serpents and other amphibia, of the larvss of insects, and of the 

 shell of the Crustacea, and the fall of the leaves of the trees. This 

 may be called ordinary or natural reproduction. The stag's horn, or 

 antler, as it should be more properly called, is a mass of true bone, 

 possessing the structure and characters of osseous substances. In its 

 early state it is soft, and traversed by large vessels, which must be 

 reproduced every time the new horn is formed. This annual repro- 

 duction constitutes, in many points of view, one of the most remark- 

 able phenomena of animal physiology. 



The cuticle of the snake is separated every year, and comes off as 

 a complete sheath, excepting the aperture, through which the animal 

 escapes ; the covering of the cornea is shed with the rest of the exter- 

 nal integument. Crustaceous animals, for instance, the crab and lob- 

 ster, have a skeleton, which surrounds and contains their soft parts, 

 and which serves, at the same time, the purposes of a skin. When 

 it has attained its perfect consistence, it grows no more ; but, as the 

 soft parts still increase, the shell separates, and is detached, being 

 succeeded by a larger one. The calcareous bodies in the stomachs ot 

 these animals performing the office of teeth, are shed with the shell. 



The second, or extraordinary kind of reproductive power, is that 

 by which wounds, fractures, or any accidental mutilation or loss ot 

 parts of an organized body are remedied or restored. This exists in 

 very different degrees in different departments of the animal kingdom. 

 In man, and such animals as are nearly allied to him, the property is 

 very limited, although sufficiently active to be capable of remedying 

 the effects of great injuries. If a bone be broken, a muscle or tendon 

 divided, or a piece of skin destroyed, processes are set up in the parts 

 by which restoration is accomplished. The ends of the bones are 

 joined by an osseous substance, which gives to the part its original 

 solidity ; the tendon regains its firmness and power of resistance ; the 

 muscle can contract again and move the points of its attachment ; 

 and the surface of the body is covered by a new piece of integument. 

 The functions of the parts are restored ; but the newly formed matter 

 can be always distinguished from the original composition of the body, 

 and possesses a weaker vitality. For, in some cases, old ulcers have 



