No. 633] SHORTER ARTICLES AND DISCUSSION 369 



To make the statement general, we can say that illness is a con- 

 dition caused by the cooperation of a series of factors, of which 

 some are genetic, heritable, given in the composition of the indi- 

 vidual's germ, and others are non-genetic, influencing the indi- 

 vidual from the outside. In different combinations of other 

 causes, individual factors can have a very different influence. 

 In certain cases, therefore, different factors can be looked upon 

 as the one which tips the scale, and. consequently as "the" 

 pathogenic moment. 



The discovery of microorganisms and their role in disease has 

 relegated other pathogenic causes to the background, and espe- 

 cially in those diseases where presence of the specific micro- 

 organism can always be demonstrated. 



In some diseases the presence of a specific microorganism is 

 not demonstrated, and an important non-bacterial factor seems 

 to be the chief determining cause (some cases of carcinoma and 

 of traumatic diabetes). In other cases, presence of a specific 



factors play an important role. Tuberculosis is a typical in- 

 stance. And finally we know diseases, in which it appears as if 

 presence or absence of a specific microorganism constitutes the 

 almost exclusive cause of the difference between affected and 

 healthy individuals (plague). 



In the first group, diseases in which microorganisms play no 

 role, the factors which cause the abnormal condition can be real 

 environmental factors, but in some instances they are clearly 

 genetic factors, developmental factors transmitted through the 

 germ, genes. "We know real hereditary diseases, where an in- 

 herited, genotypic peculiarity seems to be the causating factor 

 (hemophily, Huntington's chorea, Daltonism). 



In the second group, in those cases, therefore, where predis- 

 position seems to have an influence comparable in its magnitude 

 to infection, this predisposition can have very different causes. 

 In some cases the cause of a predisposition is very clearly non- 

 genetic, environmental (pneumonia after influenza, tuberculosis 

 of the joints after trauma). In other cases, however, inherited 

 constitution is very probably an important factor. 



