SEGMENTATION 



61 



mentation and pattern as the visible result. Could we analyse 

 these simultaneous phenomena and show how it is that the places 

 of chemical differentiation are determined by the system of 

 division, progress would then be rapid. It is here that all 

 speculation fails. 



E 



Figs. 7 and 8. Two examples of imperfect division in the vertebrae of a python. 



I, the vertebra 147-150 from the right side, showing imperfect division between 

 the 148th and 149th. The condition on the left side of this vertebra was the same. 



II, the dorsal surface of vertebrae 165-167. On the right side the 166th is double 

 and bears two ribs, but on the left side it is normal and has one rib only. 



Many attempts have been made to interpret the processes of 

 division and repetition, in terms of mechanics, or at least to 

 refer them to their nearest mechanical analogies, so far with 



