66 SYDNEY H. VINES. 



stage in the development of the embryo of all Cormophytes is the 

 division of the oosphere (central cell — germinal vesicle) into two 

 cells, one of which is more particularly devoted to the formation 

 of the embryo, and may be specified as the " embryonic cell," 

 the other forming a structure which maintains for a time the 

 connection between the embryo and the structures in which it is 

 embedded, and to this the name " embryophore" may be given. 

 Among the lower Hepaticse the plane of this first division is 

 nearly vertical, but in the Jungermanniese and in the true 

 Mosses this plane is horizontal. The relation existing between 

 these segments may be made evident by supposing the oosphere 

 of the lower Hepaticaj to be rotated through 90° in sucli a way 

 that its embryonic or anterior cell may come to occupy the same 

 position as that of the corresponding cell of the Mosses. The 

 relations existing between the segments of the oospheres of 

 ferns, of Marsilia, and of Salvinia, and those of the oosphere of 

 Isoetes, may be indicated in a similar manner, and it will be 

 found that the anterior cell of the embryo of the former plants 

 correspond to the superior cell of the embryo of the latter. In 

 Selaginella, in Conifers, and in Angiosperms, the embryonic crll 

 occupies the inferior position. In order to compare the embryo 

 of one of these plants with that of a Pern, for instance, it would 

 be necessary to imagine the oosphere of the Yeni to have been 

 rotated through 90*^ in a direction opposite to that in which it 

 had to be rotated in order to be comparable with the embryo of 

 Isoetes. 



Whatever may be the relative position of the embryonic cell 

 to the embryophore, whether it be anterior to it, or above it, or 

 below it, the organs to which it gives origin suftice to indicate its 

 true nature in all cases. In the Liverworts and Mosses it gives 

 rise to a mass of tissue, from which the sporogonium is formed, 

 and which is morphologically a thallome. In the higher Cor- 

 mophytes this is the case in the early stages, but at a later period 

 difl'erentiation takes place into caulome and phyllome, and appa- 

 rently, in some cases, such as Selaginella and Conifers, roots also 

 may be developed from it. In Mosses and Liverworts the embryo- 

 phore forms the seta upon which the sporogonium is borne, but 

 no differentiation takes place. This is the case also in some of 

 the higher forms. In Salvinia the foot is formed from the whole 

 embryophore, and apparently the suspensor of Selaginella and of 

 Conifers is formed in the same way. These facts justify the conclu- 

 sion that the suspensor of Selaginella and of Cojnfers is completely 

 homologous with the foot of Salvinia and with the seta of Mosses 



' S(:la<,nncll:i and tlie Conifers (CJ^innospcrnis ?) must be regarded as 

 possessinf^ uo true jjriniary roots. JSucb rools arc developed only from a 

 segment of the embryospore. 



