50 



PROBLEMS OF RELATIVE GROWTH 



In general, it would appear that the existence of a growth- 

 partition coefficient is the most fundamental fact in consider- 

 ing relative growth of parts, and that when true constant 

 growth-coefficients or constant differential growth-ratios are 

 found, they represent special limiting cases of this more general 

 conception. 



Let us now consider three further examples which support 

 this conclusion. I have mentioned regeneration. I shall deal 

 with this more fully in a later chapter. Here it suffices to 

 recall the fact that in an animal capable of full regeneration, 

 any organ, heterogonic or not, will, after amputation, be 

 restored in favourable conditions to its normal proportionate 



II III IV V VI VII VIII IX x XI XII 



50 

 40 

 3 - 

 20- 

 10 



126 



Fig. 30. — Decrease of growth-coefficient during regeneration in the legs of 



Sphodromantis bioculata. 



The abscissae represent moult-stages. The ordinates are growth-quotients : i.e. the ratio of the 

 length of the leg at a given moult to its length at the preceding moult. The dotted line represents 



the mean growth-quotient (1-26 = V 2 ) for normally-growing limbs. The solid line is the curve for 

 a middle-leg amputated before the Illrd moult (mean of 3 specimens). 



size. In other words, during the process of regeneration its 

 growth-ratio will be much higher than normal, and will gradu- 

 ally sink until it reaches the normal value, at which it will 

 then continue. This emphasizes the generally accepted idea 

 that regeneration is simply a special case of growth, and 

 furthermore makes it clear that here at least the normal growth- 

 ratio of an organ merely represents a limiting value. Thus, 

 as was suggested above with regard to deer-antlers, relative 

 size of organs appears to be determined in the first instance 

 as an equilibrium between amount of material in the organ 

 and amount of material in the body, the equilibrium being 

 determined according to our general formula y = bx k . If the 



