338 GENERAL PHYSIOLOGY 



likewise decomposed by strong galvanic currents, so that the 

 living substance is killed and disintegrates. 



Thus, external causes of death are superficially clear and distinct, 

 although the details of their actions are still largely unknown. 



It is entirely different, however, with the, internal causes of 

 death. They are still very obscure. Many investigators believe 

 that, there are no internal causes of death that are based 

 upon the properties of living substance, and they explain 

 the appearance of death in old age in people who have never 

 been ill by the gradual accumulation of small, imperceptible 

 disturbances during the whole life. This is the most frequent 

 explanation of the phenomenon. But it appears very insufficient. 

 Johannes Miiller ('44) was not satisfied with it. In the chapter 

 upon the Mortality of Organic Bodies in his handbook, he says : 

 " The question why organic bodies perish, and why organic 

 force passes from the parts producing it into the young, living 

 products of the organic body while the old parts die, is one of the 

 most difficult in all general physiology. We are unable to answer 

 this question, but can merely present the associated phenomena. It 

 is insufficient to answer that inorganic influences gradually 

 wear away life, for then the organic force would be obliged to 

 begin its diminution at the beginning of the individual. Yet it is 

 well known that at the time of puberty organic force is still so 

 complete that it multiplies itself in the formation of germs. 

 There must, hence, be a very different and deeper-lying cause 

 that conditions the death of individuals, while assuring the trans- 

 mission of organic force from one individual to another and in 

 this way its immortality." Many such objections may be made. 

 Were the view correct that death is brought about by the summa- 

 tion of the actions of external injuries, it would be expected that 

 a man who lives very regularly and avoids as much as possible all 

 harmful things would necessarily live much longer than one who 

 lives irregularly and exposes himself to many hardships. But, 

 even if such a difference in the duration of life should occur, in 

 many cases it would always be minute, for the oldest men have 

 not lived much beyond 120 years, and not all of these persons 

 have followed an especially regular course of life. Another circum- 

 stance comes in. In all men, without exception, whether during 

 their life they have been exposed to the greatest or the least dangers, 

 whether they have been often or never ill, or whether they have 

 had this or that disease, the same phenomena of old age finally 

 appear, consisting of atrophic processes of almost all organs. 

 With special reference to the last circumstance Cohnheim ('77-'80) 

 rightly indicates another explanation in saying : " The constancy 

 with which, no matter whether many or few, and especially what 

 pathological phenomena have occurred in the life of an individual, 

 ■A more or less pronounced atrophy appears in all organs of his 



