Strictly speaking, what is it that limits the vital activity of the individual, 

 already specialized, cells of the highly organized organism? To this question, 

 Shmal'gauzen gives the following answer: "We believe the cause of death to 

 be . . . the limitation of growth. The genesis of death is connected with the 

 progressive development of a stable higher individuality of limited dimensions 

 and strictly determinate shape with a fully harmonious relationship of the parts. 

 In all complex animals, there is some internal apparatus that establishes the 

 limits of growth and is passed on to the next generation, just like the other signs 

 of organization. This apparatus, at the same time, also limits life to certain 

 norms, since a limitation of growth is a limitation of the assimilative activities, 

 without which it is not possible to have a complete restoration of functional 

 damage. We designate incomplete restoration as attrition" (I. I. Shmal'gauzen, 

 1926). 



The nature of this internal apparatus is not sufficiently clear. In this 

 connection, Shmal'gauzen writes as follows: "This internal apparatus may be 

 intracellular — as, for example, in the form of a well known supply of enzymes, 

 which are used up in the course of successive divisions, and may be extracellular 

 in the form of the specific hormones that inhibit the cell division that leads to an 

 increase in the dimensions of the body in animals with limited growth" (1938). 



Shmal'gauzen did a great deal for the study of the characteristics of growth 

 of bacterial cultures and higher organisms and rightly stressed the significance 

 of the increasing differentiation of the cells in the lowering of the tempo of 

 growth and multiplication of the cells. He also stressed (together with G. S. 

 Maynot) ( 1 926) the significance of differentiation in the process of lowering the 

 autoregeneration of protoplasm during the first periods of ontogenesis. 



There are, however, some very substantial shortcomings in the concept of 

 aging developed by I. I. Shmal'gauzen. First of all, we cannot agree with the 

 statement that the growth rate of indifferent cells remains uniform during the 

 entire course of ontogenesis. Moreover, the very existence of indifferent cells 

 that are qualitatively identical at all ages is doubtful. 



Furthermore, Shmal'gauzen's idea of "internal factors" that determine 

 the duration of the life of the specialized cells is at least insufficient. In the first 

 place, as has already been shown earlier (in our examination of I. R. 

 Tarkhanov's theory), any theories that involve an expenditure of vital forces, 

 enzymes, vital substances, and so forth, that are initially stored in them are 

 clearly unsound. In the second place, although we cannot deny the very con- 

 siderable significance of the age-linked changes in hormonal influences in the 

 organisms of higher animals, the processes of aging ripen in all tissues without 

 exception, i.e., also in the tissues of the glands of internal secretion, and for this 

 reason the causes of aging cannot be sought only in a change in the formation of 

 one or another hormone or even all the hormones as a group. 



The prominent Russian physicist P. P. Lazarev (1928-1938) made a very 

 original contribution to the development of the science of aging. Specifically, 

 he studied the rate of the age-associated decline of the sensitivity of a number of 

 analyzers (of sensory organs) . In particular, he studied the mechanisms of the 

 weakening of optic sensitivity with old age. Having established the rate at 



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