tics of the age-linked changes in the nerve cells, especially the storage of "senile 

 pigment" in them and the degradation of the nucleoli. Mil'man made a 

 thorough investigation of the dynamics of the change in the weights of organs 

 in the course of ontogenesis and found that "the organs that grow for the longest 

 time are the lungs, heart, and arteries, the organs that supply the organism 

 with food and also with one of the most important substances, namely, oxygen. 

 These are followed immediately by the intestines, so that we find the same thing 

 in the complex organism as in the simple one: the feeding surface of the body 

 increases for the longest time, since in man and animals this is not the skin but 

 the vessels and intestines." 



It was during this same period that Mil'man formulated the first statements 

 of his theory of aging as a process of starvation (oxygen, food) of the central 

 parts of the cells and of the organs at a distance from the periphery. Growth, 

 increasing the dimensions of the individual cells and worsening the conditions 

 under which oxygen and nutrients are furnished to them and to entire organs, 

 gives rise to a lowering of vital activity, atrophy, and destruction (death). 

 This draft of Mil'man's theory, later worked out in detail, was first published in 

 1901 (Das Wachstum und das Alters). 



A number of studies in the field of the theory of aging and death were pub- 

 lished in 1900-1907 by the prominent zoologist and zootechnologist N. M. 

 Kulagin. 



Starting in 1912, such eminent Russian scientists as A. A. Bogomolets 

 (1912-1946), S. I. Metal'nikov (1912-1937), M. S. Maslov (1913-1947), P. Yu. 

 Shmidt (1915-1924) G. N. Speranskiy (1914-1948), and A. V. Palladin (start- 

 ing in 1916) began almost simultaneously their investigations of physiological 

 aging. 



The flowing of the scientific creativity of almost all these scientists falls 

 into the post-Revolutionary period; for this reason, their fundamental studies 

 will be reported later. S. I. Metal'nikov formulated his theory of aging some- 

 what earlier (1912-1917). 



One of the eminent zoologists who did a great deal of work on the physiol- 

 ogy of the digestion of infusoria, S. I. Metal'nikov (1912-1937), developed in a 

 particularly thorough fashion his view of the heterochronicity of aging of 

 different tissues and organs. He was one of the founders of the theory of aging 

 as the result of differentiation and specialization of the protoplasm and lowering 

 of the vitality of the cell under the conditions to be found in higher organisms. 

 "Progressing in one direction, the cell must necessarily regress in other direc- 

 tions." ". . . And the higher and stronger this organization as a whole, the 

 more solid and integral this new individuality of a higher order, the greater 

 will be the enslavement of the individual elements that enter into it (cells, V. N.). 

 Thus, the evolution of the entire organic world progresses in two different, and 

 as it were, opposite directions. At the same time that the complex multicellular 

 organism gradually perfects itself and progresses on the principle of division 

 of labor and specialization of the individual elements, i.e., cells, its components 

 regress in many respects." (S. I. Metal'nikov, 1917). Thus, "a multicellular 

 differentiated organization already carries within itself the embryo of future 



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