204 KANSAS UNIVERSITY QUARTERLY. 



According to the theory of evolution nature throws off useless 

 members; therefore, in races living in the torrid zone we would 

 expect a total disappearance of the cold-spots as being no longer 

 useful. But if the above experiments are to be relied upon, such is 

 not true in the present case, as we find the highest number of cold- 

 spots on the individuals of those races inhabiting the torrid zone. 

 It may be, however, that what appeared to be an increased number 

 of cold-s])ots was due to hyperaesthesia of the existing end-organ. 

 Nevertheless I suspect that climate may produce hypersesthesia or 

 anaesthesia of the temperature nerves, but that there is no marked 

 difference in the number of end-organs in members of different races 

 living under like conditions of temperature. 



If it is true that man has a common origin and climate has pro- 

 duced such marvelous changes in color, it certainly would not be 

 illogical to conclude that climate had caused the inhabitant of the 

 torrid zone to be less sensitive to heat and the inhabitant of the frigid 

 zone less sensitive to cold than the inhabitant of the temperate zone. 



Following the theory of evolution, and supposing the number of 

 end-organs to have decreased, many generations would be required 

 to show any perceptible difference in the number of end-organs; 

 but supposing anaesthesia of the existing end-organs to have taken 

 place, then but few generations would be required to show a very 

 marked difference. Moreover, we would expect to find this change 

 gradually taking place, at least until the average temperature is no 

 longer a source of discomfort to the inhabitant. I think, however, 

 that we may safely conclude that if there is any difference in the 

 number or sensitiveness of the end-organs in the different races, it is 

 only because of a difference in climatic conditions, and is not due to 

 racial distinctions. 



