﻿CCRRE.XT LIT ERA TIKI: 



and to the plants, but occurs also, to some degree, in the higher animals as 

 well, and even in man a limited rejuvenescence, at least in some tissues, is 

 possible. One sees the process of senescence everywhere in living nature and 

 it appears under various guises. Thus in the higher forms, and indeed in all 

 forms, the process of sexual or gametic reproduction and the life cycle are in 

 reality nothing but expressions of processes of senescence and rejuvenescence. 

 The sex cells are senescent cells, which by uniting with each other accomplish 

 their rejuvenescence and form a new, young individual. This conception is 

 in sharp contrast with the current Weismann-Galton view of a perennially 

 young germ plasm, separate from the soma. Instead of the germ plasm being 

 young and retaining its constitution unchanged in the soma, as such a theory 

 requires, the germ cells are the most highly differentiated and oldest cells of 

 the body, and they grow old in their development, just as the soma grows old. 

 They are indeed parts of the soma, and the influence of the environment on 

 these cells is just as pronounced as upon the soma cells, and there is no theoreti- 

 cal objection to the inheritance of acquired characters. 



The first chapter of Part I is an especially clear and readable statement of 

 the various theories of the constitution of the organism, and the author points 



corpuscular theories of inheritance. 



"An orderly progressive development of a definite character is inconceivable in 

 an organism composed of a very large number of independent ultimate units, each 

 capable of growth and reproduction, except under the influence of some controlling 



such theories represent the last word of science concerning the physico-chemical con- 

 stitution of the organism, then we must all be vitalists, whether we admit it or not." 



The corpuscular theories necessitate an entelechy to arrange the corpuscles, 

 as Driesch and others have seen. It is the corpuscular theory of living matter 



turn in this chapter, the corpuscular, the chemical, and finally the physico- 

 chemical theory of life phenomena, based on the colloidal substratum of living 

 matter. Of the last theory a particularly clear account is given, and the organ- 

 ism compared most happily to a river. 



"Neither water alone nor the banks and the bed alone constitute the system which 

 we call a river; and in nature the banks, the bed, and the current have been associated 

 from the beginning. Here, also, structure and function are connected as in the organ- 

 ism: the configuration of the channel modifies the intensity and course of the current, 

 and the current in turn modifies the morphology of the channel by deposition at one 



