PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 313 



vascular anatomy, morphology has become vastly more useful in 

 solving phylogenetic riddles. Anatomy, formerly a somewhat 

 isolated and 'dry subject, has, since its association with taxonomy, 

 physiology, ecology, and phylogeny, taken on new life, while, 

 with the development of modern microtechnique, cytology has 

 become a most useful phase of morphology. 



Due to permanence of embryonic tissues and consequent 

 continuation of growth in plants, conclusions regarding ho- 

 mology are rather uncertain when extended beyond closely related 

 groups. Better knowledge of alternation of generations has, in 

 recent years, rendered studies of homology more complex, since 

 we must avoid homologizing structures which have distinct 

 phylogenetic histories. Likewise, recent studies of vascular 

 anatomy have shattered many ideas formerly held regarding 

 probable lines of descent among higher plants. Cytological 

 studies have, at the same time, aided greatly in correcting erro- 

 neous notions regarding plant phylogeny in general. 



Many ideas regarding homology, phylogeny, and consequent 

 taxonomic disposition, once expressed with confidence, are now 

 known to be improbable or impossible. We cannot assert longer 

 that any pteridophytes arose from Anthoceros-like ancestors, if 

 indeed from any bryophyte-like plants. Likewise the ancestry 

 of gymnosperms has been pushed back to the Cycadofilicales, and 

 we no longer argue for direct descent of the former from a 

 Selaginella-like ancestor. Limits of space prevent further similar 

 discussion, except to state that our ideas concerning the origin 

 of angiosperms and the relationships of monocotyls and dicotyls 

 have been greatly modified by recent studies in vascular anatomy, 

 which show that certain forms of seed-plants formerly supposed 

 to be primitive are degenerate and not entitled to the importance 

 given them in former phylogenetic schemes. 



The non-vascular portions of vegetative tracts must receive 

 treatment similar to that which is being given to the vascular 

 tracts before we may have a firm basis for final conclusions 

 regarding ancestry. Among the ascomycetes and other fungi, 

 studies of both vegetative and reproductive areas and whole life 

 histories are rapidly changing our views regarding taxonomic 



