106 WONDERS OF ORGANIC LIFE. 



rendering the couch so uneasy that the sufferer 

 exclaims: "Would God it were even!" and 

 at even, "Would God it were morning!" 

 Deut. xxviii. 67. On the other hand, without 

 that bodily fatigue which renders " sleep sweet 

 to the weary," a period of natural sleep will 

 alternate with a natural period of wakefulness. 

 This at least is observable in the higher animals, 

 among which, in the course of every twenty- 

 four hours, a portion of time varying in its 

 length requires to be devoted to slumber. This 

 period of repose may be broken for a time, but 

 the interruption cannot be carried beyond a 

 certain limit of duration, when sleep will, in 

 spite of every effort to the contrary, assert its 

 authority. The most anxious nurse in the 

 sick-chamber, accustomed to watching as she 

 may be, requires a portion of repose. Even 

 grief at length yields to sleep. 



To cold-blooded, animals sleep at short in- 

 tervals is, perhaps, less necessary than it is to 

 warm-blooded animals. Their temperature is 

 little above that of the medium they inhabit, 

 and their muscular irritability is extreme. Yet, 

 although fishes cannot exclude the light from 

 their eyes, by means of eyelids, they sleep, 

 and the eye loses* its perception of surrounding 

 objects. They choose out some obscure spot for 

 repose, or float on the surface of the water, 

 basking in the beams of the sun. The pike, 

 for example, thus slumbers, and in this state is 

 often hauled upon the bank by means of a run- 

 ning noose of wire, (at the end of a stout rod,) 



