THE GENERAL CONDITIONS OF LIFE 339 



body in old age, in my opinion speaks very evidently for the idea 

 that the conditions of senile atrophy, so to speak, are physio- 

 logical." Minot ('90, '91) also adopts the same standpoint in 

 his researches upon growth and the phenomena of old age. In 

 fact, when man is considered not as something completed and 

 unchangeable ; when, rather, his whole development is observed, 

 and it is seen how, although living always under the same 

 external conditions, he changes gradually after birth ; how even in 

 childhood many organs, such as the thymus glands, normally 

 atrophy, although not the slightest injuries from the outside act 

 upon them ; and how later in all women even in the prime of life 

 the sexual organs degenerate, etc., etc., it can no longer be 

 doubted that senile atrophy, which leads finally to death from the 

 feebleness of old age, is simply the end of the long developmental 

 series that man, like every animal, must pass through during his 

 individual life. In reality there is no standstill in the life of the 

 organism. As the adult organism develops gradually from the 

 small egg-cell without the slightest change of its external vital 

 conditions, as is the case in many animals living in the water, 

 so it develops also, although at a different rate, gradually farther 

 to a senile, and finally to a dead, organism. The egg-cell is the 

 beginning, death in old age the natural end of an unbroken 

 development, the cause of which lies in the peculiar composition 

 of the living substance of the egg-cell. It would, hence, be more 

 correct, in place of the current view that death is conditioned by 

 the continual summation of external causes, to believe that the 

 causes of so-called natural death exist in the living organism 

 itself. 



This view is justified at once if the history of death be con- 

 sidered, not simply with reference to mankind, but comparatively. 

 The fact that the idea of death as an end-result of the develop- 

 mental series appears so late in the history of science is closely 

 associated with the prevalent view, that man, when grown, has 

 finished his development and exists for years and decades in a 

 stationary condition. This view is thoroughly false, and is due 

 simply to the fact that man's development takes place much more 

 slowly during his adult life than during his embryonic and youth- 

 ful stages. In reality, development never ceases. Changes are 

 seen clearly enough when the conditions of the adult are com- 

 pared at long intervals of time. Although no new organs are 

 formed in the meantime, the man of thirty years is a different 

 being from the man of forty years, the man of forty from the man 

 of fifty and sixty. A stationary condition is never present ; cell- 

 division, upon which from the egg-cell on all development depends, 

 takes place in adults and even in old men, although it becomes 

 constantly slower and slower. What is difficult to recognise in 

 man is shown at once by a glance at the relations that prevail 



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