INTENSITY IN DIFFERENT PLANES OF SPACE 97 



length-growth falls off notably to a much greater extent than 

 it does in the nipper dactylus. In the nipper, breadth-growth 

 is approximately constant in all joints, while depth-growth 

 decreases distally. In the crusher, on the other hand, depth- 

 growth increases steadily, and breadth-growth markedly, from 

 ischium to propus, to fall slightly in the dactylus ; (it should 

 be recalled that the rates of growth are taken relative to the 

 claw's own carpus-length, not to an independent standard in 

 the body). Perhaps the most interesting point is the change 



20 



Homarus: 



crusher 



10 



8 



nipp 



en 



14- 



10 



m. 



c 



distal 



m 



c 



distal 



B 



Fig. 54. — Probable change in the ratio between growth-intensity in depth 



and that in length (solid line) and the ratio between growth-intensity in 



breadth and that in length (dotted line) along the axis of (A) the crusher-claw 



and (B) the nipper claw (right) of the Lobster. 



i, ischium ; m, merus ; c, carpus ; p, propus ; d, dactylus. 



in the ratios between the growth-intensities in breadth and 

 depth to that in length, as we pass along the axis of the limbs. 

 The present figures are based only on a few specimens, and 

 curves constructed directly from them are rather irregular. 

 I have therefore ventured to prepare smoothed curves which 

 represent to my mind the most probable state of affairs 



(Fig- 54)- 



Thus the main difference between crusher and nipper is not 

 merely one of total growth-potential, but also of the different 

 7 



