THE INHERITANCE OF DISEASE 5O9 



the Statement that the bodily machine was worn out, that 

 there was a general functional disintegration. Even here 

 complete knowledge would be hkely to show that some 

 particular functional failure was really responsible, for the 

 evidence from tissue culture work is to the effect that given 

 a suitable environment, muscle cells, cartilage, aud many 

 other tissue cells are capable of indefinitely reproducing 

 themselves and presumably of thus perpetuating their proper 

 function in a way indicative of potential immortality. 



But on the whole, death is due to particular and recogni- 

 zable causes. And those people who die young are carried 

 away by infectious processes taking form as definite diseases, 

 tuberculosis, acute lobar pneumonia, malaria, etc. Whereas 

 those who live through this period succumb to cancer, 

 degenerative disease of the organs (nephritis, arteriosclerosis, 

 etc.) or less well characterized infections such as broncho- 

 pneumonia. These facts permit of interpretation in the sense 

 that certain individuals and their relatives are more suscep- 

 tible than the average to the diseases of early life, i.e. take 

 them more severely than others and oftener succumb to 

 them. At present for want of sufficiently precise information 

 we are unable to assign values to the different factors in this 

 very complex matter. Hypothetically if the human race 

 were comprised exclusively of those we know as long lived 

 such diseases as tuberculosis and typhoid fever would be 

 unknown or would be recognized as disorders, disturbing but 

 not especially dangerous to life. Whereas if the population 

 were exclusively of the short lived, cancer, arteriosclerosis 

 and many other diseases would be practically unknown. 



ASSEMBLAGE OF CHARACTERS AND QUALITIES 



Throughout this presentation it has been evident that the 

 essential characters on the inheritance of disease depends are 

 separately transmissible units of an almost endless variety. 

 In some few instances one such unit may completely control 

 a disease condition. But in most cases not only is the disease 

 itself only partly influenced by the inheritance but even that 

 part is controlled by a number of separately inheritable unit 

 characters. Our present knowledge fails completely in so far 



