ORGANIC DEVELOPEMENT. 615 



yielding texture of the nascent organs: lastly, 

 the whole fabric is surrounded by an outer wall, 

 the building of which is begun from the dorsal 

 region, and conducted round the sides of the 

 body, till the two portions come to meet in the 

 middle abdominal line, where they are finally 

 united into one general and continuous integu- 

 ment. The eyes, which were hitherto unpro- 

 tected, receive special means of defence, by the 

 addition of eyelids, which are formed by a 

 farther extension and folding of these inte- 

 guments ; and the greater part of the surface 

 of the body gives rise to a growth of temporary 

 down, which, as we have seen, is provided as a 

 covering to the bird at the time it is ready to 

 quit the shell. But this hard shell, which had 

 hitherto afforded it protection, is now opposed to 

 its emancipation ; and the chick, in order to 

 obtain its freedom, must, by main force, break 

 through the walls of its prison ; its beak is, how- 

 ever, as yet too tender to apply the force requi- 

 site for that purpose. Here, again, we find 

 Nature expressly interposing her assistance ; for 

 she has caused a pointed horny projection to 

 grow at the end of the beak, for the special 

 object of giving the chick the power of batter- 

 ing its shell, and making a practicable breach, 

 through which it shall be able to creep out, and 

 begin its new career of life. That this horn is 



