COXIFERALES 



99 



are directed tangentially. Chamberlain 39 thinks that this tan- 

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





';-" 



E 



-r 



D 



H 



FIG. 76. Pimis Laricio, early stage in the development of the embryo : A, fusion of 

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

 nuclei from the jacket cells (/>, pollen tube; , cavities caused by inrush of con- 

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

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

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

 beginning to elongate; A- C collected June 25th, D-G July 2d; * 104. 



