272 ME. A. S. HOENE — A CONTRIBUTION TO 



The ovular bundle is directly connected with a principal bundle ; and the latter 

 divides into three, of which the median extends into the ovule (F). In another flower 

 branches from the adjacent principal bundles unite to form the ovula,r bundle. 



The diagrams I, J, K, L are drawn from sections of a biovulate ovary. The ovular 

 bundles originate from the principal bundles 1 and 5 (I, J). 



The Nature and Origin of the Floicer 



Aucuha was first of all placed 



6 



Corneis affinia " of Endlicher 



System *, but later included among the Cornese f, under a subfamily, the AucubcEe. It 

 has remained closely associated with Cornus in sul)sequent systems. 



Diverse interpretations have been made of the nature and origin of the unilocular 

 ovary. Baillon % argued the probable derivation of the ovary of Cornus (bilocular) from 

 that of Aucuha by the centripetal ingrowth of parietal placenta3, pointing out that 

 the ovary of Garrya formed a connecting-link between the two. This argument would 

 imply that the ovary is polymerous, consisting of carpels united by their margins. 



According to Eichler §, on the other hand, the ovary is monomerous. Wangerin || 

 considers it to be monomerous by reduction :— " Per understandii^e Fruchtknoten wird 



o 



»» 



Now 



hier von einen einzigen Karpellblatt gebildet " and " Cornus bildet das Zentrum dieser 

 Gruppe, von dem sich Aucitba hinsichtlich der Reduktion in Gynseciums am weitesten 

 entfernt 



the ovary of Aucuha could be easily synthesized from carpels which become 

 united by their margins, and, if this were so, Baillon's hypothesis would carry weight, 

 since the carpels retain the potentiality for centripetal ingrowth. But the\'ascular 

 evidence at present tiu'ns the scale in favour of a different explanation. The rudimentary 

 brandies at the base of the loculus recall the similarly situated infra-locular branches in 

 Marlea platanifolia. It was suggested in this case that the iufra-locular branches 

 extend as axial or septal bundles iu septate forms of Marlea hegonifolia. Hence, in tlie 

 case of Aucuha, it seems not unreasonable to suppose that the curious infra-locular rudi- 

 ments represent an axial or septal system that existed in the primitive flower. If this 

 were so, the ovary was probably ;quadrilocular and hence tetramerous. The primitive 

 ovary of Aucuha may be likened to that of riburnum, the efi"ect brought about by 

 abortion, however, being difi"erent ia the two cases. It was deduced for Viburnum, from 

 the peculiar floral morphology and vascular structure, that the parietally placed ovule 

 was originally axially suspended— the abortion of septa being evidently accompanied by 

 the displacement of the axially borne ovule and axial vascular tissue to a peripheral 

 position. But anomalies of the kind described for Viburnum do not occur in Aucuha, 

 so we may conjecture that the axially suspended ovules present in the primitive Aucuba 

 disappeared with the septa, leaving only a single parietally borne ovule in the ovary. In 



8. Endlicher, Gen. PI, 798. 



H. Baillon iu Bull. Soc. Linn. Paris (1877) 139. § 



li W. Wangerin m Engl. Bot. Jabrb. xxxviii. Ileft2 (1906) 6, 50. 



t S. Endlicber, Gen. PI. Suppl. iv. part 3. 18. 



