264 



MORPHOLOGY OF GYMNOSPERMS 



the mother cell and its successors (fig. 291). The cells of this jacket, 

 which invests not only the central cell but also the succeeding egg, 

 develop the usual features of tapetal cells, with densely staining cyto- 

 plasm and large nuclei; but their special feature is the conspicuous 

 thickening and pitting of the walls bounding the central cell (and 

 egg). At first it was supposed that through these pits the jacket 

 cells emptied their contents into the enlarging central cell and egg 



289 



Figs. 289-292. — Pinus Laricio: development of the archegonium; fig. 289, arche- 

 gonium initial, May 28; fig. 290, neck and central cells, June 2; fig. 291, central cell 

 just before cutting oflE ventral canal cell, June 18; fig. 292, cutting off ventral canal 

 cell, June 21; X104. 



(28), including the bodily transfer of their nuclei. In this way the 

 central cell and egg were thought to be packed with food, their cyto- 

 plasm being filled with large and deeply staining masses (more promi- 

 nent in the egg) which were regarded as the nuclei contributed by 

 the jacket cells. Even after Steasbukger had shown that these 

 deeply staining masses are not nuclear in nature, but that the best 

 organized are the so-called "proteid vacuoles," Arnoldi (55) 

 described the behavior of the migrating nuclei, reporting them to 

 become amoeboid in the jacket cells, to squeeze through the pits, and 

 to regain their form in the central cell and egg. Nuclei were also 



