244 ME. A. S. HOEXE— A CONTEIBUTION TO 



Passing tlien to the Cornaceae, the author selected Corolda and Marlea, genera with 

 unilocular or hilocular ovaries, and traced the structural changes accompanying the 

 reduction from two loculi to one. With the aid of all the available facts it was then 

 possible to analyse and interpret the uniovulate Cornacese, and the single terminal ovule 

 was found to be of multiple origin. The sterilization series evident in the Caprifoliaccje 

 extends by way of Samhucus to the Cornaceae, where vestiges of ovules are unknown, and 

 the conclusion reached that the ovaries or loculi of the Cornaceee were primitively 

 pluriovulate is supported by the direct evidence deduced from their own structural 

 peculiarities. 



A series has been traced in the direction of the loss of carpellary autonomy by way of 

 the AraliacesB, Caprifoliacese, and Cornaceae that culminates in the reduced ovary of 

 Aucuha, which in appearance and structure simulates a single inferior carpel. 



Structural synthesis in the flower is accompanied by a corresponding economic 

 advance in the development of the vascular system. The dorsal and lateral bundles of 

 the carpels, and the traces of the perianth and stamens that exist as independent series 

 in Aralia are in the Caprifoliacese represented by one series, and the latter family 

 exhibits a still further economical advance reaching in Fibtirmim the condition obtaining 

 In the Compositse, where the bundles in the single series are reduced to half the sum 

 of the petals and stamens. Two lines of advance towards the evolution of the single 

 series have been traced, one presented by Aralia, Davidia, and Marlea, and the other 

 exemplified by the Hamamelidaceae. 



The ovule in the Caprifoliaceae and Cornacece has advanced far beyond the evolu- 

 tionary stage exhibited by the Hamamelidaceae, but whereas there is little deviation 

 from a single type in either the Hamamelidaceae or Caprifoliacese, the ovules of 

 Cornaceae present diverse forms and structures. The nucellus of Cornaceae presents 

 some resemblance to that of the Eosaceae on the one side, and on the other through 

 Helicingia to the reduced nucellus of Lilium or Inula. 



Considerable emphasis is laid upon the fact that similar stages and methods of floral 

 construction recur, not only in the same but different families, and upon the fact that 

 similar ends are attained in the same or different families by dissimilar methods. The 

 separation of the sexes occurs in several genera of Hamamelidaceae, Rosacese, and 

 numerous other families. Epigynous structures have arisen in numerous groups and 

 even in the same group by more than one device. The centripetal development of 

 parietal placentae, rendering the ovary multilocular, occurs in Castanea, Querctis, 

 Mhodoleia, and many other genera. Similar stages in the evolution of the vascular 

 system have recurred in Castanea, the Caprifoliacese, and Cornaceae, whilst similar 

 arrangements of ovules are found and the details of the vascular supply are nearly 

 identical in difi'erent families. Neither is the ovule by any means exempt. The 

 separation of one type from another; the transition from bi- to unitegumentary forms, 

 and the evolution of the exalbuminous seed has happened again and again in the racial 

 experience of Angiosperms, Convergence and parallel development are established 

 doctrines, but many authors have failed to grasp their significance. Convergence in 



