m] REGENERATION, OR GROWTH AND REPAIR 143 



proper scale we shall find that the angle which it makes with the 

 base is about 25°, of which the tangent is 46, or in round numbers |. 

 Had the angle been 45° (tan 45° = 1), the curve would have 

 been actually a rectangular hyperbola, with VT = constant. As 

 it is, we may assume, provisionally, that it belongs to the same 

 family of curves, so that F'^T'S or V^'^'T, or VT"'"^; are all severally 

 constant. In other words, the velocity varies inversely as some 

 power of the time, or vice versa. And in this particular case, the 

 equation VT^ = constant, holds very nearly true ; that is to say 

 the velocity varies, or tends to vary, inversely as the square of 



16 1i 

 days 



Fig. 38. Rate of regenerative growth in larger tadpoles. 



the time. If some general law akin to this could be established 

 as a general law, or even as a common rule, it would be of great 

 importance. 



But though neither in this case nor in any other can the minute 

 increments of growth during the first few hours, or the first couple 

 of days, after injury, be directly measured, yet the most important 

 point is quite capable of solution. What the foregoing curve 

 leaves us in ignorance of, is simply whether growth starts at zero, 

 with zero velocity, and works up quickly to a maximum velocity 

 from which it afterwards gradually falls away; or whether after 

 a latent period, it begins, so to speak, in full force. The answer 



