THE STUDY OF THE EVOLUTION OE THE ELOWEE. 247 



unilocular, completely bilocular, or bilocular in the superior portion only. The above- 

 mentioned descriptions appear to the writer to afford clear evidence that the ovary of 

 Bhodoleia is varying in the deforce of centripetal development of the placentae, and in so 

 doing exhibits a tendency to break into different types distinguished by the presence and 

 absence of a septum respectively. The ovaries of the Hamamelidoideie possess a septum 

 which renders them bilocular. 



The ovules in the BucldandioideaB are arranged in series attached, in unilocular 

 forms of BJiodoleia, to parietal placentae. In Liquidamhm% according to Shoemaker*, 

 they are developed on marginal placentae. The writer attaches some importance to the 

 method of placentation in the Hamamelidoldeae. Sargent f states that the ovules in 

 Hamamelis are suspended from the septum. Niedenzu % gives a representation of them 

 attached to the septum in JIamamelis and Corylopsis spicata, but the writer, after a 

 careful examination of several species (notably, Hamamelis virr/inica, arhorea, and 

 Zuccariniana, Corylopsis spicata, Farrotia Jacquemontiana, and Fothet^r/illa Gardeni and 

 major), finds that they are not thus attached, but borne upon parietal placentae that are 



situated immediately above the septum. 



There are some interesting- points connected with the number of ovules, and it is 

 possible to arrange certain genera in a series from those in which the ovules are 

 numerous in each loculus to those with uniovulate loculi. Shoemaker § records two 

 series in each loculus of Liqiiidambar styraciflua. Le Maout and Decaisne || note that 

 the ovules of the Hamamelideae (including BucUandia) are either solitary or numerous, 

 but in the latter case only the lower are fertile, whilst in Bisanthus cercidifolius, from 

 Baillon'sl description, the number of ovules in each series is reduced to three. 

 Eeduction reaches an extreme in the Hamamelidoideac. Here it is generally stated that 

 the ovaries possess uniovulate loculi, although Baillon** long ago described two 

 instances in which the loculi are, at first, biovulate, but later uniovulate, owing to the 

 arrestment of one of the pair, thus in Hamamelis virginica, " Bans Tangle interne de 

 chaque logo, il y a un placenta vers le haut duquel s'inserent un ou deux ovules 

 descendants. Dans ce dernier cas, I'un d'eux s'arrete de bonne heure dans son 

 developpement " ; and in Distylium " II y a dans chaque loge deux ovules dont un seul 

 prend tout son developpement." Le Maout and Decaisne ft even figure a four-seeded 

 fruit of Hamamelis. Shoemaker %% found only one example of an ovary with biovulate 

 carpels in H. virghiiana, although he examined several hundred flowers and suggests 



D. N. Shoemaker in Bot. Gaz. xxxix. (1905) 262. 



t Sargent, Silva of N. Amer. v. (1893) 1. 



X Niedenzu in Engl. ii. Prantl, Nat. Pfl.,TeU iii. Abt.2 (1891), figs. 65 (^Hamamelis) and 72 {Coryhjpnxs sftcata) 



§ D. N. Shoemaker, I. c. 262. 



il Le Maout and Decaisne, Gen. Syst. Bot;. ed. Hook. 410 (1876). 

 f H. Baillon, Histoire des Plactes, iii. 396 (1872). 



•* 



H Baillon, I. c. 390 (^Hamamelis) ; 395 {Distylium). 



ft Le Maout and Decaisne, I. e. 409. 

 t+ D. N. Shoemaker, I. c. 251. 



SECOND SEEIES. — BOTANY, VOL. VIII 



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