186 SECTIONAL ADDRESSES. 
vascular system and the stomata. The community of reproductive 
phenomena is explained by Dr. Church on the principle that reproductive 
phases are inevitable and are therefore the same in all phyla. A like 
explanation may to a certain extent be applicable to somatic features, 
some of which may be the necessary consequences of the sub-aerial trans- 
migration. Thus a polyphyletic hypothesis may no doubt be justified, 
but it urgently needs to be supported by further evidence of the actual 
existence of separate stocks among the earliest available records of a 
Land Flora. 
The study of Fossil Botany has led to results of the utmost 
importance, in widening our view of the Vegetable Kingdom and helping 
to complete the natural system, to use Solms-Laubach’s old phrase 
once more. One need only mention the Mesozoic Cycadophytes, the 
Cordaitales, the Pteridosperms, the Paleozoic Lycopods and Equise- 
tales, the Sphenophylls, and now, most striking of all, the Psilo- 
phytales, to recall how much has been gained. We have indeed a wealth 
of accumulated facts, but from the point of view of the Theory of 
Descent they raise more questions than they solve. In this address I 
have briefly touched on some of the most general and most speculative 
problems in the hope of giving an opening for discussion. It might 
have been more profitable to deal in detail with definite facts of 
observation, but recent discoveries have brought us face to face with the 
great questions of descent among plants. However imperfect our data 
may be, both as regards the method and the course of evolution, the 
problems suggested, nevertheless, make urgent claims on our attention. 
