26 THE DURATION OF LIFE. 



lives in the same manner, and finally also divides into two halves. 

 As far as these organisms are concerned, death can only be spoken 

 of in the most figurative sense. 



There are no grounds for the assumption that the two halves of 

 an Amoeba are differently constituted internally, so that after a 

 time one of them will die while the other continues to live. Such 

 an idea is disproved by a recently discovered fact. It has been 

 noticed in Eiiglypka (one of the Foraminifera) and in other low 

 animals of the same group, that when division is almost complete, 

 and the two halves are only connected by a short strand, the proto- 

 plasm of both parts begins to circulate, and for some time passes 

 backwards and forwards between the two halves. A complete 

 mingling of the whole substance of the animal and a resulting 

 identity in the constitution of each half is thus brought about 

 before the final separation *. 



The objection might perhaps be raised that, if the parent animal 

 does not exactly die, it nevertheless disappears as an individual. I 

 cannot however let this pass unless it is also maintained that the 

 man of to-day is no longer the same individual as the boy of twenty 

 years ago. In the growth of man, neither structure nor the com- 

 ponents of structure remain precisely the same ; the material is 

 continually changing. If we can imagine an Amoeba endowed 

 with self-consciousness, it might think before dividing ' I will give 

 birth to a daughter,' and I have no doubt that each half would 

 regard the other as the daughter, and would consider itself to be 

 the original parent. We cannot however appeal to this criterion of 

 personality in the Amoeba, but there is nevertheless a criterion 

 which seems to me to decide the matter : I refer to the continuity 

 of life in the same form. 



Now if numerous organisms, endowed with the potentiality of 

 never-ending life, have real existence, the question arises as to 

 whether the fact can be understood from the point of view of 

 utility. If death has been shown to be a necessary adaptation for 

 the higher organisms, why should it not be so for the lower also ? 

 Are they not decimated by enemies ? are they not often imperfect ? 

 are they not worn out by contact with the external world? 

 Although they are certainly destroyed by other animals, there is 



1 See Appendix, note 10, p. 64. 



