262 THE EVOLUTION THEOEY 



popular words and ideas in a restricted and somewhat altered sense 

 to scientific conceptions when it seems necessary. That the word 

 ' immortality ' in this case expresses the state of matters more precisely 

 and better than any other cannot be doubted, any more than we can 

 doubt that there exists in regard to natural death a real difference, 

 which we must take account of, between the Unicellulars and the 

 higher organisms. What enables the species in the case of the higher 

 organisms, like ourselves for instance, to last through ages is not the 

 immortality of the individual, of the person, but only that of the 

 germ-cells; these alone, among the cells of the whole body, have 

 retained the primaeval power. A small piece of the individual is still 

 immortal, but only a minute part, which cannot be considered as 

 equivalent to the whole, either morphologically or from the point of 

 view of the conception of individuality. Can anyone consider himself 

 identical with his children ? If any one should imagine this, it would 

 still not be the case, for he himself would in the course of time suffer 

 natural death, and his children would continue to live on until they 

 too had brought forth children, and in their turn also came to die. 

 It is quite different with an Infusorian, which never lies down to die, 

 but simply splits itself afresh into two halves which continue to live. 



It is hardly credible that such a simple and clear truth should 

 have remained so long undiscovered, and it is even more incredible 

 that since it was enunciated it should have been until quite recently 

 laughed at as false, as a piece of pseudo-science, and as valueless. 

 But it is the fate of all knowledge which rests on an intelligent and 

 comprehensive working up of facts to be attacked, until it gradually 

 bears down antagonism by the weight of its truth, and compels at 

 least a silent recognition. 



The fact that natural death made its appearance with the appear- 

 ance of a ' body,' a soma, as distinguished from the germ-cells, will 

 sooner or later compel recognition. When I pointed out above that 

 the explanation of natural death lay in the fact that it would be 

 superfluous for the soma to continue to live on unlimitedly, after it 

 had discharged its germ-cells, and so fulfilled its duty to the species, I 

 only intended to say that this was the general reason for the intro- 

 duction of natural death. I have no doubt that the actual beginning 

 of this phenomenon could have, and probably did come about in other 

 ways. Many kinds of cells in higher animals perish as a result 

 of their function ; it is, so to speak, their business to perish, to 

 break up ; this is the case with many glandular and epithelial 

 cells. It may very well be that, in many of the highly differentiated 

 tissue-cells, such as nerve, muscle, and glandular cells, the high 



