CONIPERALES 



99 



are directed tangentially. Chamberlain ** thinks that this tan- 

 gential direction of fibers is caused by the rotation of the nuclei 



^./^3i 



i- 



<*£" 



tSf: 





kir ^^' 





-s», > »^ 



!KSi?::i:^|i:^,;: 





fe?»' 





St 



,»' ^ 







Fig. 76. — Pinvs Lariaio, early stage in the development of the embryo : A, fusion of 

 male and female nuclei ; B, the first four nuclei of the proembryo, also numerous 

 nuclei from the jacket cells {p, pollen tube ; n, cavities caused by inrush of con- 

 tents of pollen tubes) ; C, the four nuclei at the base of the egg and dividing ; D, 

 the first plate of four cells ; E, a somewhat later stage, showing partial cleavage of 

 the main mass of the egg; F^ two plates of cells, the lower cells in process of divi- 

 sion ; O, the three tiers of cells of the completed proembryo, with the four free 

 nuclei above them (r, "rosette" tier; s, suspensor tier); ^T, the suspensor tier (s) 

 beginning to elongate; ^-(7 collected June 25th, D-G July 2d; x 104 



