Among the physiological indices of age-associated changes in tissues and 

 organs, they investigated the changes in the total levels of the oxidative processes, 

 tissue respiration, the activity of the individual enzymatic links in the oxidation- 

 reducdon process, glycolysis, the characteristics of energy, protein, carbo- 

 hydrate, and mineral metabolism, the composition and properties of the urine, 

 and so forth. A thorough investigation was made of the ontogenetic changes in 

 the functional capacities of the entire organism and of its individual tissues and 

 organs, the synthetic abilities of the organism, especially in connection with the 

 synthesis of proteins, formation of ATP, and oxidative phosphorylation, syn- 

 thesis of urea in the liver, protective syntheses, stimulation of tissue respiration 

 in the whole organism by various factors, the ontogenesis of the reactivity of the 

 organism to the introduction of a variety of hormones and the influence of loss 

 (removal) of a number of glands of internal secretion on its metabolism at 

 various ages, and many other matters. Studies were made of age-associated 

 changes in biochemistry and functions of denervated organs, which provided a 

 good deal of data forjudging the ontogenetic evolution of the relations between 

 the nervous system and the peripheral organs. 



Nagorniy and his pupils also conducted extensive histochemical and 

 micro-anatomical investigations, which provided a considerable amount of 

 material for age-associated histophysiology. 



All these investigations laid a broad experimental basis for recognition of 

 the major features of the age-associated changes in the animal organism as a 

 whole. 



The following very important conclusions can be drawn from these studies. 



1. The ontogenetic development of the organism from its beginning in 

 the form of the fertilized ovum to its death does not by any means represent a 

 fatal path of uninterrupted degradation of the colloidal state, biochemistry, 

 physiological functions, and macro- and microstructures. The first early stages 

 of ontogenesis are connected with an increase in many potentialities and in the 

 activity of the protoplasm. Even in later ontogenesis, there are some high poten- 

 tialities of vital activity, often found in a latent form. 



2. The aging processes in the organism appear chiefly in the form of dis- 

 turbances of synthesis, the assimilatory phase, which indicates the major sig- 

 nificance of the changes in this phase ("synthetic, reactive nodes" of the proto- 

 plasm) in the processes of ontogenesis. Along with this, aging is accompanied 

 by substantial changes in the processes of dissimilation and an impairment of 

 the reciprocal "fit" of the processes of synthesis and breakdown. 



3. The functional and biochemical evolution of organisms does not pro- 

 ceed uniformly in the various organs and tissues, also not uniformly with respect 

 to the unity of the assimilatory and dissimilatory phases of the life process. 

 With increasing age, there is an increase in the disharmony of the adjusted 

 unity of the total animal organism. 



4. With increasing age, the processes of synthesis become all the more 

 "expensive" as regards energy. An increasingly small part of the organism's 

 energy metabolism is used for the synthesis and resynthesis of the substances of 

 the protoplasm. 



35 



