PATTERNS OF DEVELOPMENTAL PROGRESS 



725 



dimensions. The method can, of course, also be used for different develop- 

 mental stages of the same species. Values and limitations of the method 

 are discussed by Huxley (1932, chap. iv). 



A few of Thompson's figures are reproduced here. In Figure 222 the 

 method is applied to carapaces of several genera of crabs. In Figure 223 



Fig. 222, A-F. — Transformations of Cartesian co-ordinates applied to carapaces of different 

 genera of crabs. A, Geryon; B, Coristes; C, Scyramathia; D, Paralomis; E, Lupa; F, Chorinus 

 (from Thompson, Growth and Form, 19 17). 



it is applied to the whole bodies, viewed laterally, of two related teleosts. 

 In this case transformation of the rectangular co-ordinates, applied in 

 Figure 223, A, to Diodon, into a system approximately hyperbolic and 

 transferring the outline of A to corresponding points in it gives, in Fig- 

 ure 223, 5, essentially the outline of Orthagoriscus, a genus closely related 

 to Diodon but very different in form. Evidently, difTerential growth is 

 much greater in the dorsiventral dimension of the posterior region in 

 Orthagoriscus than in Diodon. In Figure 224 the transformations required 



