



THEIR RELATIONS NOT CONSTANT 155 



order of disposition of the parts, or from that structural character which 

 has been held as typical, are chiefly found where they would on this view 

 be theoretically probable, viz. in the Homosporous Pteridophytes. This 

 seems to be the natural way of regarding the various types of strobilus 

 seen in early Vascular Plants : it is certainly more satisfactory than any 

 attempt forcibly to reduce them to conformity with categories based upon 

 the study of those plants which represent a later phase of evolution. 



