584 CONSTANCE 



necessity of major alterations of all proposed systematizations of this group 

 and threatens to destroy the generally accepted Alismataceae-Ranunculaceae 

 bond with dicotyledons. These are t)^ical of the corrective discipline com- 

 parative anatomy can apply to phylogenetic taxonomy. 



The rise of developmental and experimental morphology promises to tell 

 us many new and interesting things, and perhaps the solution to the age- 

 old problems of growth, differentiation, and maturation. The welcome burgeon- 

 ing of this experimental field should not, however, have the effect of labeling 

 as static and antiquated the systematic analysis and description of mature 

 tissues. Before we can determine how all mature tissues develop so marvelously 

 and intricately from the fertilized egg, we must know what and where these 

 adult tissues are. Although as a good biologist he has an intense interest in 

 the outcome of developmental approaches, the taxonomist must build his clas- 

 sifications on systematically assembled information. Another of my biologi- 

 cal colleagues, this one not a botanist, recently remarked that there are prob- 

 ably two kinds of biologists: those who are interested primarily in the origin 

 of life, and those who are interested in its various manifestations. Neither 

 he nor I were able to see why one group should claim superiority over the 

 other, nor deny importance to its scientific efforts. 



Comparative embryology, which has served systematic zoology so well, has 

 just come into its own in botany and is in its infancy of application to prob- 

 lems of botanical classification. By embryology I mean to indicate all the 

 gametophytic stages of vascular plants, including especially nature and mode 

 of development of microspores and megaspores and the embryonic and early 

 juvenile stages of the sporophyte. As you know, there has been an impressive 

 growth in analytical and comparative data on the embryo sac by Schnarf, 

 Maheshwari, Fagerlind, and Battaglia, among others. The recent books of 

 Johansen (1950) and Maheshwari (1950) indicate the marked progress in 

 this field. These data have been utilized to attempt clarification of relation- 

 ships between angiosperms and certain groups of gymnosperms, although with 

 somewhat conflicting conclusions. Certain families and genera have been 

 tested for degree of affinity on embryo-sac characteristics, with interesting 

 results. But numerous families remain untouched, and the distribution of 

 embryo-sac types does not yet present a clearly phylogenetic picture. The 

 study of microspores has expanded rapidly, stimulated by the employment 

 of microfossils as a tool for dating in various aspects of science and by recog- 

 nition that knowledge of pollens is important medically. Systematic ordering 

 of information from this area, as illustrated by the publications of Wodehouse 

 and Erdtman, to name only two, promises much of utility for plant taxonomy. 

 Already, the interrelations of gymnosperms and the two great classes of 

 angiosperms have been notably clarified by this means. 



Descriptive cytology is a child largely of the 20th Century and has enjoyed 

 a vigorous infancy and adolescence. Although chromosome number and 



