90 PHYSICAL INVESTIGATION. [PART 1. 



of man depends,, we arrive at the following results. The 

 assertion that the physical type possessed by the respective 

 races remains entirely permanent is erroneous ; it is only as to 

 the limits of certain changes that doubts exist. It is impossi- 

 ble to determine the exact influence of each individual agent, 

 or to point out its limits. The theory which has most in its 

 favour is, that mental culture possesses the greatest influence, 

 climatic conditions alone have the least, diet and mode of life 

 hold an intermediate place. Finally, the spontaneous origin 

 and transmission of new qualities appear among the most 

 influential agents in the production of differences among man- 

 kind. Still it must be borne in mind that it can only become 

 extensive in its effects among a people where cultivation has 

 obtained a firm soil, or where the original uniformity of indi- 

 viduals, both externally and internally, no longer exists, and 

 where the acquired qualities are transmitted externally to 

 succeeding generations. 



SECTION II. 



THE CHIEF ANATOMICAL AND PHYSIOLOGICAL DIFFERENCES 

 WHICH DISTINGUISH THE VARIOUS RACES. 



In the preceding section we have investigated the nature and 

 the extent of the changes to which the human frame is subject, 

 and traced them to their causes. If we are to arrive at any 

 conclusion on the question whether all the peoples of the globe 

 belong to one species, or whether specific differences exist 

 among them, we must study the anatomical and physiological 

 facts. By doing so we may learn, whether the extent of the 

 existing differences is within the sphere of physical change, the 

 causes of which are traceable. 



If we must, on the one hand, examine the differences among 

 mankind with regard to bodily shape and physical life, and the 

 changes to which they are subject, it is not the less necessary, 

 in order to arrive at any result, to compare these changes with 

 those which occur among animals standing next to man in 



