112 LIFE AND DEATH. 



its duration, not because it was contrary to its very nature to be 

 unlimited, but because an unlimited persistence of the individual 

 would be a luxury without a purpose. Among unicellular organisms 

 natural death was impossible, because the reproductive cell and 

 the individual were one and the same : among multicellular animals 

 it was possible, and we see that it has arisen. 



Natural death appeared to me to be explicable on the principle of 

 utility, as an adaptation. 



These opinions, to which I shall return in greater detail in a 

 later part of this paper, have been opposed by Gotte 1 , who does not 

 attribute death to utility, but considers it to be a necessity in- 

 herent in life itself. He considers that it occurs not only in the 

 Metazoa or multicellular animals, but also in unicellular forms of 

 life, where it is represented by the process of encystment, which is 

 to be regarded as the death of the individual. This encystment is a 

 process of rejuvenescence, which, after a longer or shorter interval, 

 interrupts multiplication by means of fission. According to Gotte, 

 this process of rejuvenescence consists in the dissolution of the 

 specific structure of the individual, or in the retrogression of the 

 individual to a form of organic matter which is no longer living 

 but which is comparable to the yolk of an egg. This matter is, by 

 means of its internal energy, and in consequence of the law of 

 growth which is inherent in its constitution, enabled to give rise to 

 a new individual of the same species. Furthermore, the process of 

 rejuvenescence among unicellular beings corresponds to the forma- 

 tion of germs in the higher organisms. The phenomena of death 

 were transmitted by heredity from the unicellular forms to the 

 Metazoa when they arose. Death does not therefore appear for 

 the first time in the Metazoa, but it is an extremely ancient 

 process which ' goes back to the first origin of organic beings ' 

 (1. c, p. 81). 



It is obvious, from this short resume, that Gotte's view is totally 

 opposed to mine. Inasmuch as only one of these views can be 

 fundamentally right, it is worth while to compare the two ; and 

 although we cannot at present hope to explain the ultimate physio- 

 logical processes which involve life and death, I think nevertheless 

 that it is quite possible to arrive at definite conclusions as to the 

 general causes of these phenomena. At any rate, existing facts 



1 ' Ueber den Ursprung des Todes,' Hamburg and Leipzig, 1883. 



