84 



MORPHOLOGY OF SPBRMATOPHYTES 



from the primary neck cell, and by periclinal divisions the single 

 plate becomes two, so that the neck is composed of two tiers of 

 cells with four cells in each tier. The recorded deviations are 

 as follows: in Tsuga Canadensis, 31a, 49, and Cephalotaxus 

 Fortunei the neck is usually two-celled, as in Cycads and Ginkgo; 

 in some Cupresseae eight cells occur in each tier; while in some 

 specis of Pinus and Picm more than two tiers of cells occur, with 

 four or eight cells in each tier. 



After the separation of the neck cell from the central cell, 

 the latter begins a remarkable increase in size and receives a 





^x 



D 



Fig. 64. — JPinus Laricio : A, arohegonium initial, May 28th ; B^ neck and central cells, 

 June 2cL ; C, central cell just before cutting off the ventral canal cell, June 18th ; 

 D, cutting oif of the ventral canal cell, June 21st ; x 104. 



large amount of nutritive material (Fig. 64, C). About it a 

 definite jacket of endosperm cells is organized, resembling the 

 venter of an archegonium. The cells of the jacket become sur- 

 charged with protoplasmic material, and their nuclei enlarge, 

 while the wall of the central cell becomes thick and very dis- 

 tinctly pitted. Through these pits Goroschankin ^® first traced a 

 continuity of cytoplasm between central cell and jacket cells. 

 Very early in its history, at the beginning of its enlargement, the 

 central cell becomes vacuolate, the protoplasmic contents forming 

 merely a wall layer, the nucleus retaining its apical position from 



