our movements possible." This formulation is very close to the remarkable con- 

 cept expressed by F. Engels, who described the life process as a means of exist- 

 ence of protein substances: ^^Life is a method of existence of protein substances^ and 

 this method of existence consists essentially in a continuous renewal of the con- 

 stituent chemical parts of these substances".^ 



Danilcvskiy confronted biochemistry with the task of studying the phylo- 

 and ontogenetic evolution of proteins and other substances of the protoplasm: 

 "Beyond a doubt, knowledge of the course and laws of the chemical evolution 

 or organs, tissues, and the organism as a whole represents one of the most im- 

 portant links in our understanding of life on earth" (a statement of his pupil 

 N. F. Baymakov, 1904). 



Danilcvskiy suggested (1886) that synthetic (plastic) processes are accom- 

 plished in the organism with the aid of special plastic enzymes. Effective func- 

 tioning of these enzymes requires the action of the so-called stimulin (a specific 

 stimulator). In ontogenesis, there is a continued expenditure of the supply of 

 stimulin, which is laid down in the embryo and there bound to protein sub- 

 stances. When the protoplasm is in an active state, stimulin is dissociated from 

 its combination with proteins and acts on the plastic enzymes, giving rise to a 

 heightened rate of synthesis (neoformation) of proteins. Even in youth, the 

 stimulin supply is sharply decreased, and this causes a decrease in the growth 

 rate. With old age, the organism retains only insignificant traces of stimulin, 

 which leads to a catastrophic lowering of the neoformation of the proteins of 

 the protoplasm. 



In essence, therefore, Danilevskiy's theory of the biochemical basis of 

 aging is close to I. R. Tarkhanov's concept of the depletion of a hypothetical 

 vital substance in ontogenesis and has the same fundamental defect: an acknowl- 

 edgement of the formation of the vital substance in phylogenesis and a non- 

 recognition of this process in ontogenesis. Unlike Tarkhanov, Danilevskiy 

 suggested that stimulin can be regenerated in youth, although not in its totality. 



Danilevskiy (1891) was the first to establish qualitative and quantitative 

 differences in protein composition between young and adult animals (puppies 

 and adult dogs). 



In 1886, S. D. Kostyurin (a pupil of V. V. Pashutin) studied changes in 

 the macro- and microstructure of the human brain with aging, and in 1 890 he 

 investigated the effects of Brown-Sequard extract from the seminal glands of 

 the senile organism (the first steps in age-associated endocrinology). 



During the period from 1900 to 1917 (up to the Great October Socialist 

 Revolution), there was further development of Russian age-linked physiology, 

 biochemistry, and morphology. A number of new major trends and schools 

 arose during this period, and some of these reached their flowering after the 

 Revolution. 



The investigations of M. .S. Mil'man (1900-1940) the eminent Russian 

 histologist and one of the leading Russian ontophysiologists, began in 1900. 

 In the years before the Revolution, he worked principally on the characteris- 



» F. Engels: Anti-Duhring, 1948, p. 77. 



12 



