Ill] THE EFFECT OF TEMPERATURE 107 



Again as physiologists have long been aware, there is a marked 

 difference in the variation of weight of the different organs, 

 according to whether the animal's total weight remain constant, 

 or be caused to diminish by actual starvation ; and further striking 

 differences appear when the diet is not only scanty, but ill-balanced. 

 But these phenomena of abnormal growth, however interestmg 

 from the physiological view, are of little practical importance to 

 the morphologist. 



The effect of temperature*. 



The rates of growth which we have hitherto dealt with arc 

 based on special investigations, conducted under particular local 

 conditions. For instance, Quetelet's data, so far as we have used 

 them to illustrate the rate of growth in man, are drawn from his 

 study of the population of Belgium. But apart from that 

 "fortuitous" individual variation which we have already con- 

 sidered, it is obvious that the normal rate of growth will be found 

 to vary, in man and in other animals, just as the average stature 

 varies, in different localities, and in different "races." This 

 phenomenon is a very complex one, and is doubtless a resultant 

 of many undefined contributory causes ; but we at least gain 

 something in regard to it, when we discover that the rate of growth 

 is directly affected by temperature, and probably by other physical 



iiber die Beeinfliissung der Wachstum durch die Ernahrung, Berl. klin. Wochenhl. 

 LI, pp. 972-977, 1913, etc. 



* The temperature limitations of life, and to some extent of growth, are summar- 

 ised for a large number of species by Davenport, ^x^er. Mor2')}iology , cc. viii, xviii, 

 and by Hans Przibram, Exp. Zoologie, iv, c. v. 



