DEATH IN ORGANISMS 265 



scendant of pre-existing parental cells. These statements 

 have been criticized from various angles by different 

 scientists, but the fact nevertheless remains that " no one- 

 celled organism ever lost an ancestor through death." 



Death in Multicellular Organisms. — The many- 

 celled organisms are likewise descendants of pre-existing 

 parents, yet in this group death is a regularly recurring 

 process. Wherein lies the difference in this particular 

 between the multicellular and unicellular species? The 

 answer is forthcoming when the development of the first- 

 named class is critically examined. The egg-cell of the 

 hen, for example, by repeated divisions gives rise to an 

 individual in which the cells become differentiated into 

 two very distinct types, those of the body proper and the 

 germ cells. The body is the more obvious and impressive, 

 and appears to be the more important. It is fitted for a 

 definite set of conditions and displays a series of com- 

 plex activities of gathering food, avoiding enemies, and 

 begetting and caring for the young. Nevertheless it is 

 a mere sheath for the reproductive elements that it 

 nourishes and protects, and which alone are capable of 

 producing the succeeding generation. 



In the lowest multicellular organisms, such as Gonium, 

 each cell reproduces its kind, while in higher types, where 

 the division of labor is more complete, only the germ-cells 

 have retained this power. The body when emptied of 

 its reproductive cells thus becomes a worthless husk, and 

 while the protoplasmic stream flows from germ-cell to 

 germ-cell, death claims the body at each generation. 



Death an Advantage to the Species. — The food 

 supply of every species of plant and animal is limited; 



I more individuals are produced than can possibly exist 

 throughout the normal lifetime, and it therefore is evi- 

 dent that in the unceasing struggle for existence the fit- 

 test individuals should persist if the species is to be kept 

 up to a high standard. Man is no exception to this rule. 

 Whatever our sentiments may be in the matter, it must 



