No. 508] 



STUDY OF VASCULAR ANATOMY 



231 



duced and simplified structure, which it presents in the 

 vascular series, has made it particularly suitable for the 

 initial stages of modern morphological development. 

 With the discovery of zoidogamous fertilization in Cycas, 

 Ginkgo and the lower fossil gymnosperms, the revelation 

 of the remarkable mode of fertilization in the Araueari- 

 nese, simulated at least in the Podocarpinese, the uncover- 

 ing of the phenomenon of breech fertilization in the lower 

 Amentiferge and the elucidation of other striking phe- 

 nomena connected with the male gametophyte, we have 

 come to realize that it is the male sexual generation and 

 the sporogenous apparatus, producing it, which carry the 

 highest phylogenetic interest. The origin of the seed 

 from the megasporangium, although beyond question on 

 general morphological grounds, still largely lacks illumi- 

 nating facts to lighten the darkness of its past. 



The more complicated sporophytic generation of the 

 higher plants, except as to its special sporogenous struc- 

 tures, has much more recently been attacked by evolution- 

 ary morphologists. Its very complexity, however, and 

 the possibility of following its structures into the remot- 

 est past, make it of the greater importance from the 

 standpoint of the theory of descent. The evidence derived 

 from its study serves, moreover, to control, amplify and 

 enrich the conclusions reached from the standpoint of the 

 morphology of the gametophyte alone. We have, accord- 

 ingly, begun to realize that the anatomical examination of 

 the sporogenic organs of vascular plants is quite as im- 

 portant as the cytological study of the process of sporog- 

 eny itself, and "that the fern-like mode of fertilization 

 obtaining in the lower gymnosperms, living and extinct, 

 has its not less important or significant equivalent in the 

 presence of cryptogamic or centripetal primary wood. In 

 fact, with the realization of the importance of the sporo- 

 phvtic generation in the higher plants, we are now for the 

 first time in a position to begin our phylogenetic book- 

 keeping by double entry, with greatly added security as 

 to the final accuracy of the balance we may strike. 



