314 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 



and phylogenetic disposition, and the same is no less true of the 

 algae. Studies in the morphology of plants of all groups with 

 a view to reconstruction of our ideas of homology, taxonomy, 

 and phylogeny will in the future advance botanical science great- 

 ly ; but past experience indicates that no theories should be ac- 

 cepted without thorough testing. 



Paleobotany, which has come to its own within the last two 

 or three decades, is, in its botanical aspect, mainly a phase of 

 plant morphology and phylogeny. Through recent paleobo- 

 tanical studies, we have been able to throw much light on phylo- 

 genetic problems. Comparisons of the minute morphology of 

 living forms with that of fossil plants have enabled us to reach 

 certain conclusions regarding relationships, some of which have 

 been stated above. Recently, such studies have proved the ex- 

 istence, during carboniferous time, of fern-like gymnosperms-, 

 which seem to connect modern types with homosporous lepto- 

 sporangiate ferns more closely than with the Lycopodiales. 

 Much argument regarding phylogeny formerly based on mod- 

 ern pteridophytes is now pushed backward to plants of a former 

 geological age. Paleobotany seems to have proved the multiple 

 origin of heterospory, of the seed-habit, and of secondary growth. 

 Yet little is known of fossil plants beloAv the vascular series; and 

 fossil botany is still largely an unexplored field, which is destined 

 to aid vastly more than it has yet done in phylogenetic studies, 

 though we may scarcely hope for much help among lower plants. 



Another promising field of botanical research that has en- 

 gaged the attention of several American botanists in recent years 

 is experimental morphology, which overlaps both physiology and 

 ecology in determining the relations of structure and function 

 to environment. The goal is to ascertain ranges of variation and 

 the factors which determine these variations. The experimental 

 morphologist, therefore, deals with function quite as much as 

 with form. Ordinary morphology might regard the enclosing 

 walls the essential parts of an oogonium, an antheridium, an 

 archegonium, or a sporangium ; but the experimental morpholo- 

 gist would look especially to the fertile cells within. Experimen- 

 tal morphology has proved recently that external vegetative tis- 



