which this sc'nsiti\it\ drcjps in elderly persons from 60 to 80 years of age, Lazarev 

 extrapolated this curve further and found that it drops to zero (to the level of 

 the axis of abscissae) for an age of 120-150 years. In other words, the sensi- 

 tivity of the nervous system disappears completely at this extreme age. 



This gave further physiological evidence that the normal duration of 

 human life slujuld exceed a hundred years. 



After N. P. Cundobin, the problems of tlic piiysiology and pathology of 

 childhood were further investigated by M. S. Maslov (1913-1947). 



A number of studies on the characteristics of metal)olism in early childhood 

 were made by N. F. Tolkachevskaya (1947-1955) and her co-workers. 



In addition to age-associated physiology, there has been an ever broadening 

 investigation of age-associated biochemistry, beginning with A. Ya. Danilevskiy. 

 The need of such investigations was formulated in a program paper by V. S. 

 Gulevich entitled "Significance and course of development of comparative 

 biological chemistry of animals" (1933). In it, Gulevich speaks, first of all, of 

 the timeliness of the establishment of this new branch of science: "It would ap- 

 pear somewhat strange to speak of tlie significance of a non-existent science, but 

 the time has now come when comparative biological chemistry must enter the 

 fraternity of the other disciplines and when we must consider, along general 

 lines, what must be the content of this inchoate science and its significance, as 

 well as the lines along which it should develop." 



Gulevich asserted that the comparative-evolutionary approach should be 

 the guiding orientation of comparative biochemistry: "Biochemical studies of 

 man must not be isolated from the corresponding studies of other classes of 

 animals: in the study of his chemistry, man must not be separated from the rest 

 of the tremendous and \aried animal world. Just as comparative anatomy re- 

 veals an uninterrupted evolutionary chain from the simplest animals to man, so 

 in biological chemistry it will be necessary to undertake a systematic study of 

 the chemical statics and chemical dynamics of animal organisms on all zoologi- 

 cal levels and to bind the study of man to comparative biological chemistry." 



This was written long before the comparative biochemical studies by E. 

 Baldwin (1938) and Florken (1941). 



V. S. Gulevich indicated that phylogeny is organically connected with 

 ontogeny. In the region of age-associated biochemistry, he pointed out a series 

 of courses for investigation: embryochemistry, the chemical study of ontological 

 development as the accelerated and shortened course of phylogenetic develop- 

 ment, and the biochemistry of the child organism. 



An extremely valuable contribution to the development of age-associated 

 biochemistry was made by A. V. Palladin (starting in 1916) and his pupils. 

 As early as the publication of his early monograph called "Study of the forma- 

 tion and isolation of creatine in animals" (1916), he reported a series of investi- 

 gations connected with the age-associated characteristics of the organism. 

 Later on, Palladin made a detailed study of the characteristics of creatine 

 metabolism in children (1926-29) and then studied, in a number of papers, 

 the changes in the creatine content at various ages and during the period of 

 embryogenesis in a number of laboratory animals (1936-1938). In his subse- 



28 



