64 SURVEY OF THE REPRODUCTIVE PROCESS 



tajn rudimentary organs are formed — the plumule, radicle, 

 and cotyledons, representing the axis, root, and leaves of 

 the future plant — and it is on differences in this respect 

 that the great division into Monocotyledons and Dicotyle- 

 dons is based.* 



The whole process of development is more rapid than in 

 the Coniferae, there being no arrest in the grorfi of the 

 pollen-tube, and the flowering and seeding of the plant 

 being generally accomplished in the same season ; but there 

 is an entire agreement in the main feature — the adhesion 

 of the ovule to the parent plant till the maturation of the 

 embryo. In some exceptional cases the connection is not 

 entirely broken off even then ; the inextricable thickets of 

 Mangrove, with which swampy tropical shores are fringed, 

 are said to be due to the property which the seeds of this 

 tree have of Q-erminatino; while still attached to the branch.i* 



From this sketch of the reproductive process, it appears 

 that the Angiospennous Phanerogamia differ both from 

 Coniferse and from the higher Cryptogamia (Rhizocarps, 

 Ferns, &c) — firstly, in the absence of any accessory cells at 

 the summit of the embryo-sac, like those which form the 

 crown of the corpusculum and the styloid neck of the arche- 

 gonium ; secondly, in the non-development of any distinct 

 tissue in the ovule, like the albuminous body or the 

 prothalhum ; in compensation for which, as it were, Ave 

 have, thirdly, an additional outer envelope — the germen or 

 ovary. From the Cryptogamic orders they differ farther in 

 the separation, as it would seem, of the two elements by 

 the continuous membranes of the pollen-tube and embryo- 

 sac. In Phanerogamia we have two distinct genital canals, 

 but neither of them corresponds to the archegonial canal 



* In^the Orobranchese and OrcMdacese, tlie embryo reaches no higlier 

 development, in the ripening of the seed, than a globular mass of cells. 



t In apples, &c.j the seeds are sometimes seen in a state of germina- 

 tion. 



