THE STUDY OF THE EYOLVTION OF THE FLO WEE. 291 



I 



5. The flowers of certain genera admit of the following interpretation : 



a. Cornus: The ovary is bilocukr by reduction from a quadricarpellary primitiye 



type. It is analogous to that of Smnhucus. 



h. Al 



ingiimi: Tlie ovary is unilocular by reduction from the bilocular type found 

 in Marlea begonifolia, and reduced from a form primitively polycarpellary. 

 <?. Auciiha : The flowers have become unisexual since the attainment of epigyny. 



The ovary was primitively quadricarpellary and quadrilocular. The septa 

 subsequently disappeared, but the lower portion of tbe carpels remained 

 unmodified. The ovules, originally numerous, became numerically reduced 

 until only a single parietally suspended one remained. 



d. Garrya : The flower is hypogynous as already noted by Wangerin. 



e. Griselinia : The flowers have become unisexual since the attainment of epigyny, 



and a tendency towards apetaly finds its expression in G. lucida. The ovary 

 was primitively tricarpellary and trilocular, at all events in its upper portion, 

 but the septa disappeared, leaving the lower portion of the carpels unmodified, 

 but involving the displacement of an ovule that was primarily axially situated. 



6- Progressive abortion in the ovary reaches its limit in this family — the ovaries of 

 Davidia and Helw'mgia are multilocular, the change from the bi- to the unilocular 

 condition can be traced in CoroMa, and the ovaries of Aucuha, Nyssa, Alanr/'mm, and 

 Griselinia are unilocular. 



issive sterilization has proceeded still further than in the Hamamelidaceae 

 and Caprifoliaceae, nearly all the genera have reached the level of the extreme cases in 

 these families, and the ovary or loculus is absolutely uniovulate. 



8. The general series that has been traced in the direction of the loss of carpellary 

 autonomy culminates in Aucuba, where, owing to the absence of septa and to the 

 parietal situation of the ovule, the gynaecium appears to consist of a single carpel. 



9. Both the Cornacese of Harms and the Cornacece of Wangerin are heterotypic, 

 but this fact is masked, owing to parallel development and convergent organization. 



7. Pros? 



5. FINAL DISCUSSION. 



J 



The Interpretation of Resemblances and Differences. — Hitherto that which 



may be called the Principle of Eesemblances has held amazing sway. Drawing first 

 breath, as it were, in the days of Eay, virile before the birth of the ' Origin of Species,' 

 it has evolved throuirh the length of two centuries, and reached its zenith as presented by 



3*" ""^ ^^"O 



Adolf Engler in ' Die Natiirlichen Pflanzenfamilien ' just over twenty years ago. Almost 

 oa the eve of the publication of Engler's mighty work, a new era in botanical history 

 had dawned. In 1889, De Vries's ' Intracellulare Pangenesis' had been given to the 

 world, an essay which Bateson * declares " remarkable as a clear foreshadowing of that 

 conception of unit-characters which is destined to play so large a part in the development 

 of genetics," to be swiftly followed by * Die Mutationstheorie ' t ; whilst the year 19U0 

 brought with it the triple rediscovery of Gregor Mendel. 



W. Bateson, Mendel's Principles of Heredity,' 5 (1913). 



t H. De Vries, ' Die Mutationstheorio ' (1901-3). 



