132 BIOLOGICAL ASPECTS OF HUMAN PROBLEMS 



It has been pointed out that the main cause of 

 disturbed health is the entry of pathogenic bacteria 

 into the body, and it has been intimated that the 

 injury inflicted by these bacteria arises in consequence 

 of poisons formed by them. It appears to be true 

 that analysis of the facts relating to disease shows 

 the occurrence of poisoning to be the essential cause 

 of nearly all departures from health. In saying 

 this, it is meant to use the term "poisoning" in a very 

 broad sense, to include every injurious effect due 

 to the accumulation of chemically acting materials 

 in any portion of the body. If we think of poison- 

 ing in this sense, we are at once brought face to face 

 with the realization that there is really no sharp line 

 of demarcation between health and disease. We are 

 accustomed to think of disease as something quite 

 distinct from health, just as moralists are apt to think 

 of evil as something easily separable from good. 

 Close scrutiny shows us that a clear distinction is as 

 little possible in one case as in the other, in at least 

 a considerable group of instances. A specific in- 

 stance will serve to make this clear. It is a fact that 

 in childhood the process of intestinal digestion is 

 carried on, in very many individuals, for long periods 

 at a time with singularly little putrefactive decompo- 

 sition, despite the millions of bacteria present. 

 The absorption of certain putrefactive products is 

 therefore minimal in these children. Often, however, 

 we find children in whom these substances are 

 formed and absorbed in moderate amounts. Yet 



