4 BIOLOGICAL ASPECTS OP HUMAN PROBLEMS 



formed without a clearer recognition of the essen- 

 tially fundamental attributes of the human animal 

 organism. People have long suspected that the 

 human body is in truth a machine of extreme com- 

 plexity of function. But that the human body 

 should be regarded as something more than a mere 

 machine is only natural. Yet the resemblances 

 between the most refined mechanisms of human 

 design and the human body are so many and so 

 fundamental that it is no light task to trace fairly the 

 resemblances and differences. What is true of the 

 entire animal organism in this respect is true of 

 each individual cell in the living body; namely, that 

 while an ever-increasing proportion of its activities 

 may be explained on the basis of physicochemical 

 laws, there still remain functions that defy known 

 methods of analysis. 



The mechanistic conception of the animal body is 

 essentially of modern origin. Harvey's discovery 

 of the circulation of the blood paved the way to the 

 recognition of the heart as an efficient force pump ; 

 and more recent studies have made it clear that a 

 proper distribution of nutrient material and of 

 oxygen depends on the integrity of various mechani- 

 cal arrangements connected with the circulatory 

 system. In general, the maintenance of a good 

 blood supply is of the first importance for the 



