higher Cnjptogamia and Phanerogamia. 243 



ciated with the germ-vesicle of all but the lowest plants, though 

 totally independent of it, that we can scarcely investigate the 

 course of the one without to some extent entering upon the con- 

 sideration of the nature and relation of the other. These struc- 

 tures may be called accessory or investing organs, and as ex- 

 amples of them I may mention, the various coats of the ovule, the 

 pro-embryonic frond of Ferns, and the cellular layer which en-^ 

 virons the embryonal germ of a Moss, and which afterwards con- 

 stitutes the spore-case. I may repeat that these investing organs 

 belong to the organic structure of the parent plant ; and they do 

 so belong to it, whether they are maintained in their connexion 

 with it, as are the primine and secundine of the ovule, or whether 

 they are disconnected from it, as is the prothallus of a Fern. 

 The first growth therefore to be recognized as independent de- 

 velopment, is the vesicular coat which is formed around the con- 

 centration of protoplasmic or germinative matter within the em- 

 bryo-sac. The contents of this vesicle are the immediate result- 

 ant of the parent life, the first formative act of the new existence 

 being the cell-wall enclosing these contents. In the unimpreg- 

 nated stage of the germinal vesicle, its derived power has become 

 isolated, for its processes of assimilation and the varying dispo- 

 sition of the protoplasm must be considered acts of its separate 

 vitality. 



I have further to notice generally, that in all plants the sepa- 

 ration of the young plant from the old, — of the newly-derived 

 existence from the parent life, is accompanied by a condition of 

 rest, or rather of the capability of resting; for instance, the 

 Phanerogamous embrj^o within its testa, the vesicle of a Cryp- 

 togam within its spore-case. 



This resting stage is always carefully arranged for by the pro- 

 vision of suitable integuments and store of endospermous matter. 

 We have seen that the resting stage is attained at varying 

 epochs of development in different orders of plants, and that a 

 more or less amount of development is attained within the par- 

 ticular receptacle of the parent plant. Special organs are modi- 

 fied to suit the special circumstances of each case. Thus, in An- 

 giospermous Phanerogams, for sustentative and nutritive pur- 

 poses, the coats of the ovule are maintained in their connexion 

 with the axis by means of a funicular cord; whereas the homo- 

 logous organ of Filices — a free development subsequent to the 

 resting stage — is cellular fibrillse or rootlets. These fibrillse of 

 the prothallus of the Fern are, however, not only homologous 

 with the funiculus of the ovule of Angiospermous Phanerogams, 

 but their function is the same, namely that of affording support 

 and nutriment. The funiculus of the ovule then, and the fibrillse 



16t 



