60 SYDNEY H. VINES. 



view of Strasburger/ in accordance with which the whole central- 

 cell of the corpusculum is to be regarded as being the true 

 Gosphere, and therefore as the homologue of the germinal vesicle 

 of Angiosperms, as opposed to that of llofmeister,- according to 

 which a formation of secondary germinal vesicles takes place 

 within the central cell, one of which is fertilised and gives rise to 

 the embryo. Strasburger considers the secondary germmal vesicles 

 described by Hofmeister to be merely vacuoles. 



One of the principle changes to be observed in the oosphere 

 of Pinus sylvestris in consequence of fertilisation is the disappear- 

 ance of its nucleus, and this is immediately followed by tiie 

 appearance of four new nuclei in that portion of its protoplasm 

 which is most distant from the neck of the corpusculum (archego- 

 nium). Each of these nuclei exercises an influence upon the proto- 

 plasm which surrounds it, in consequence of which the granules of 

 the j)rotoplasm are arranged in lines radiating from the nucleus. 

 Intermediate between any two nuclei there is observable a vertical 

 row of large granules, which defines the limits of each cell and 

 the position of the future cell-wall, and a horizontal row (in sec- 

 tion) of similar granules marks otf the whole mass of protoplasm 

 in which the four nuclei lie from the remaining protoplasm of the 

 oosphere. These nuclei then divide, and four new cells are formed, 

 which lie in one plane above the ])receding, from which they are 

 separated by a cellulose wall. The four upper cells then divide, 

 and in this way three layers, each consisting of four cells, are 

 formed. The cells of the uppermost layer remain as a rosette 

 in the base of the oosphere, those of the middle layer elongate 

 considerably and form the suspensors, and those of the lowermost 

 layer give rise each to an embryo (fig. 2) . 



The similarity between the process of the development of the 

 embryo of Pinus and the general account previously given of 

 that of Angiosperms is at once apparent. In both cases the cell, 

 from which the new individual is to be developed divides primarily 

 into two, from the upper of which the suspensor is developed, from 

 the lower the embryo itself. The principal difference is that in 

 Angiosperms, it is the whole oosphere which thus divides into two, 

 whereas in Gymnosperms the dividing cell has been derived, by a 

 process which is essentially one of free-cell formation, from the 

 oosphere. 



In the further development of the embryo, there is one par- 

 ticular in which the process occurring in Gymnosperms ditfers 

 from that in Angiosperms, and that is the mode of origin of the 



' 'Befruchlunr^ der Conifcreu,' ISGO, p. IS, also ' Die Coiiiferen und 

 Gnetacecn,' 1872, p. 279, and ' Zcllbildung uud ZcHtheilung,' 2te Aufl., 

 1877, p. 18. 



' ' On the Higher Cryptogamia,' p. 412, Ray Society, 1862. 



