ON THE ORIGIN OF DEATH. 11/ 



inherent in germ-plasm. Weismann attempts to show- 

 that to the species death is an advantage. All animals 

 are liable to accidents, and if animals were to live on for 

 all time, many would be maimed and useless. By far his 

 strongest arguments, however, are based on other facts. 



Favorable variations in nature are seized on by 

 natural selection and preserved, whether they be an 

 advance towards greater specialization or retrogressive. 

 Long since, Darwin pointed out that small wings were 

 an advantage to insects living on islands where strong 

 winds prevail, for those which had large wings would 

 be more apt to be blown out to sea, and so lost to 

 the race. Hence a survival of the fittest has maintained 

 short-winged varieties. Small eyes buried in fur are 

 an advantage to burrowing animals, such as the mole ; 

 hence this variety has been preserved. So, also, the 

 complete disappearance of the limbs of snakes which 

 squirm through small holes and clefts. Limbs would 

 be a disadvantage and a hindrance. 



When, however, degeneration of disused organs con- 

 fers no benefit on the individual, the explanation is 

 different. Thus the eyes of insects, crabs, fishes, and 

 amphibia, which live in caves, have undergone degenera- 

 tion ; yet this can hardly be of advantage to them, for 

 they could live quite as well in the dark with well- 

 developed, as with rudimentary, eyes. The efficient 

 eyes of allied forms living in the light have been main- 

 tained in their perfection by the survival of those only 

 having good eyes. Is it not evident that when such 

 animals come to live in darkness, natural selection 

 will cease to act, and deficient eyesight result .'* If 

 those with imperfect eyes intermingled with those with 



