mi 



NATURAL HISTORY OF PLANTS. 



bearing on its inner face the two cells, adnate for their whole 



len<;th, and eacli dcdiiscing- by a longitudinal cleft.' The carpels, 



^ also indefinite, consist each of a one-celled ovary, 



(^ surmounted by a horn-shaped style, bent outwards at 



jp\ tlie tip.' The whole of the inner face of the ovary 



■ j and style is traversed by a longitudinal groove, of 



■ ] which the everted edges are covered above with 

 m^ numerous stigmatic papillae. In the inner angle of 

 ^^ the ovary is seen a parietal placenta bearing two de- 

 scending anatropous ovules, with the micropyle looking 

 upwards and outwards.^ The fruit consists of a large 

 number of finally dry carpels' inserted on the now woody 



Each opens when ripe along the dorsal suture (fig. 168),' 



Magnolia 

 grandtjlora. 



Fig. 16i). 



Seed. 



axis. 



to free one or two seeds which remain for a variable time sus- 

 pended to a slender filament (fig. 169).' Each seed has three 

 coats ;' the outermost is quite fieshy ; the middle hard and testa- 



' The pollen of M. grandijiora L. consists of 

 praiiis of the shape of a grahi of corn, somewhat 

 acute at each end, and with a large longitudinal 

 fold due to the inflexion of the outer coat. H, 

 MoKL has already pointed out that it has the same 

 form as in most Monocotyledons {Ann. Sc. Nat., 

 SIT. 2, iii. 221). In conta(;t with water the form 

 changes, so that the fold disappears, the length 

 is diminished, and the ends are rounded. The 

 exterior is covered with projecting granulations of 

 a fatty consistency, and the superficial and deep 

 parts of the grain present a marked contrast in 

 colour. The centre is darkest, and finely grannlar. 

 M. mncrophylla Micux., has similar pollen 

 grains, hut more elongated and fusiform. 



- Tlie style varius greatly in form and size 

 from the short somewhat dilated horn of M. 

 grandijiora L., or the shghtly hooked subulate 

 jjoint of M. Yulan Dksf., to the revolute and 

 almost plumose style of M. glauca L., in which 

 last the papilla; of the margins of the internal 

 groove are not simple, but branched. 



* When adult, they become more or less oblique, 

 and sometimes even horizontal. At the same 

 time, the micropyle inchnes somewhat to the 

 lateral walls of tlie cell, and the rajihes approach 

 one another on the middle line. They have two 

 coats. There are sometimes three ovules in the 

 ovary of M. Yulan Desf. and macrophylla 

 Miciix.; the third is then superior and nearly 

 median. 



■•In several species they long possess a fleshy 

 consistency, and a jiiiikish or yellowish tint, re- 

 calling that of certain succulent pericarps. In 

 some, the woody endocarp separates from the 



thicker and less consistent mesocarp after de- 

 hiscence. 



" Dehiscence in most species takes place simply 

 by a longitudinal cleft, of which the borders 

 separate to form two lateral panels. In some 

 others, as M. macrophylla MiCHX., besides the 

 two panels, we perceive the dorsal rib, woody, and 

 like a long subulate filament, only attached to 

 the receptacle by its base, and free fi'om all ad- 

 hesion to the lateral walls. 



'' This filament consists of tracheae, which are 

 continued into the raphe of the seed; the turns 

 of tlieir spirals separate as the seed descends. 



^ The curious organization of these seeds, with 

 an outer fleshy coat, which LiXN.?;us called an aril, 

 has been a source of long discussions to the bota- 

 nists of our times (Miees, Contrib.,\.\Q'2,VlA,2i\l; 

 Hooker F. & Tiioiis., Fl. Ind., i. 77; A. Gray, 

 in Hook. Journ., vii. 213). The origin of the 

 outer coat has been attributed to various organs, 

 some making it a special sac emanating from the 

 pliicenta, and finally enveloping the whole seed j 

 while others consider it one of the proper seed 

 coats, singularly modified after a certain age. 

 This last interpretation alone appears satisfactory 

 to us, as will be seen in the following extract 

 from the special article we recently devoted to 

 this subject {Compies liendus, Ixvi. 700; Adan- 

 soiiia, viii. 159) — " The so much disputed origin 

 of the fleshy coat of the seed of Magnolia is de- 

 monstrated both by its development and by its 

 histological structure. It is formed by the hyper- 

 trophied cells of the primine, rich fii'st in starch 

 and afterwards in oily matter. Moreover, its 

 thickness is traversed bv the tracheal bundles of 



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