20 Mr. J. Miers on the Development 



ward to form the primine, while its margin remains as the 

 micropyle. Neither Mirbel's view nor Fritsche's notion is 

 confirmed by my observations; the many cases I have seen 

 convince me that the early growth of the nucleus and secun- 

 dine proceeds wholly from the budding-point or future chalaza, 

 which is the point of termination of the tracheal vessels imbedded 

 in the substance of the main support or placentary sheath. This 

 mode of growth is most conformable to the ordinary law of de- 

 velopment, and is quite analogous to the production of the sepals, 

 petals, stamens, disk, and ovary from the budding-point of the 

 pedicel, which is furnished in like manner, and for the same 

 purpose, with tracheal vessels. It is a far more reasonable in- 

 ference than the gratuitous assumption of Fritsche, that the 

 ovular tunics are generated by the spontaneous separation of the 

 epidermis, which doubles itself up, so as to produce those tunics 

 by its further expansion. 



After this early period, the further increment is very evident : 

 the bottom of the channel I have described, with the budding- 

 point, grows downward, becoming by degrees an oblong pouch 

 with a broad, open mouth, suspended by the funicular point of 

 its origin, at the same time that the nucleus and secundine 

 enclosed in it grow upward; this continues till we have a com- 

 plete and suspended anatropal ovule, ready for impregnation, 

 at which period the papillary apex of the nucleus is exposed 

 within the open mouths of the tunics ; during this successive 

 growth of the ovule of Amy g dolus, the apex of the nucleus never 

 changes its zenithal aspect, while the chalaza as constantly points 

 to the base of the cell ; there is no one-sided growth of the 

 tunics, which grow equally upon all sides ; and there is no in- 

 version of the nucleus or of its coats, according to the opinion 

 generally entertained. In this development, all is beautifully 

 contrived to attain by the most simple means the main function 

 — the generation and perfection of the future embryo, for which 

 purpose the apex of the nucleus is retained always in near prox- 

 imity to the placenta by means of its short funicle ; and close 

 to this point we see, as Brongniart long since demonstrated, a 

 lamellar plate, to which the funicle is attached, which plate, 

 formed of a peculiar tissue, is terminated by a fringed border 

 that overhangs the mouths of the ovular tunics : the articulated 

 cells forming this process bear the name of tela conductrices, 

 because they serve to conduct the pollinic influence to the point 

 of the nucleus, by which means the embryo-sac is impregnated. 

 I mention here this point of structure, because the position of 

 this fascicle of cells, in relation to the raphe, is sometimes an 

 tndication of importance, as I shall have to show in the case of 

 ihe Rhamnacece. 



