MAGNOLIACEJE. 



133 



ceous, the inner one membranous. This last is immediately sur- 

 rounding the fleshy albumen, which contains a small dicoty- 



Magnolia purpurea. 



Fig. 170. 



Longitudinal section of seed. 



Magnolia Yulan. 



Fig. 171. 



Flower without its perianth. 



ledonous embryo towards its apex (fig. 170). In the flower of 

 Magnolia Yulan, of which it has been proposed to make a special 

 genus under the name of Yulania,^ the lower portion of the recep- 

 tacle forms a dome-shaped swelling (figs. 167, 1j1), into the base 

 of which is inserted the perianth. This, instead of consisting of six 

 petaloid leaves, and three others, green like those of an ordinary 

 calyx, usually presents nine leaves in three whorls, all similar, 



the raphe and its branches. As these vessels 

 contain little but gas when mature, we have 

 found a means of disclosing the path of the vas- 

 cular network, by leaving the seed for some time 

 in tincture of iodine. All the cells then become 

 violet, and almost black, while the tracheae remain 

 only of a clear brown tint. We can now follow 

 and dissect out all the tracheal network in the 

 thickness of the parenchyma, much as we isolate 

 the injected vessels of an animal. The bundle in 

 the raphe, while giving forth branches on either 

 side, proceeds to the chalaza, where it bends up 

 to enter the interior of the seed. We must here 

 describe a peculiar orifice intlie testaceous middle 

 coat, diametrically opposite the micropyle, and 

 never encroached upon by the incrustations of the 

 deep coat. Tiie physiological importance of this 

 new organ will be realized — a canal, of definite out- 

 line, which can be traversed by a very fine metallic 

 style without any destruction of tissue, and which 



we call the ' heteropyle.' The testaceous coat, 

 which retains its primitive orthotropy, is thus 

 furnished with two polar apertures. As to the 

 superficial fleshy envelope, the older botanists 

 termed it an aril, an appellation which recent 

 authors have not adopted; and yet it forms a 

 sort of generalized aril, far more worthy of the 

 name than those partial hypertrophies of the 

 outer seed coat to which it is now-a-days usually 

 applied." 



' SPAcn, Suit, a Buffon, vii. 462. In this genus 

 the author includes three species : 1-^ I', con- 

 spicua (Magnolia conspieua Salisb. — M. Yulan 

 Desf.) ; 2° Y. japonica, (M. ohovata Thg. ; — 

 M. denudata Lamk.; — M. discolor Vext.; — 

 M. purpurea Curt.) ; of this M. Sonlangiana 

 Sweet and liliiflora Lamk., are considered 

 simply forms; 3° F. Cohus {M. iomentosa 

 Thg.; — M. gracilis Salisb.; — M. Kobui 

 DC). 



