174 ANGIOSPERMS, 
with that one of the axial row which develops into the embryo-sac. 
The view held by the author is that the hypodermal cells in both cases 
are macrospore mother-cells. In Zum this macrospore mother-cell 
becomes at once the macrospore, while in Aed/edorus it gives rise to 
four spores. In both cases the reduced number of chromosomes is 
present, and the egg-cell of Zzdium is hereditarily the equivalent of 
the egg-cell in Helleborus. The number of cell-divisions elapsing 
between that period in which the reduced number of chromosomes 
appears and the differentiation of the sexual cells is of no importance, 
since in many ferns, for example, thousands of cell-divisions occur 
between these points in ontogeny. It seems, therefore, that the view 
held here not only does no violence to either the facts of morphology 
or cytology, or to the most widely accepted theory concerning the 
significance of the reduction of the number of chromosomes, but it is 
also in complete harmony with these facts. 
THE MALE GAMETOPHYTE. 
As in the case of the embryo-sac, the development of the male 
gametes in the microspore or in the pollen tube, the male gameto- 
phyte, is so well known that only the briefest mention of it is necessary. 
In the microspore of Zz/éum, in which the cytological details are 
probably best understood, the antheridial or generative cell is clearly 
differentiated from the remaining cytoplasm of the spore by a plasma 
membrane. The generative cell is moon-shaped orcrescenticin Lzdéum 
candidum and L. martagon, and its cytoplasm behaves somewhat 
differently toward certain stains,’ so that the contrast between the gen 
erative cell and the cytoplasm of the tube cell is often very striking. 
Strasburger (’98), who attributes a fibrillar structure to the cytoplasm 
of the generative cell, regards it as kinoplasm, and since some cyto- 
plasm accompanies the male nucleus into the embryo-sac, the theory 
may not be without significance. In ZLz/éum and in many other 
Angiosperms the generative or antheridial cell divides in the pollen 
tube to give rise to the two male gametes, but in some instances this 
division takes place in the spore. Each male gamete consists, there- 
fore, of a nucleus surrounded by a small portion of cytoplasm derived 
from the generative cell. 
Nothing need be added here concerning the growth of the pollen 
tube toward the egg-cell of the embryo-sac. The result is the same 
whether the tube enters through the micropyle or chalaza. The end 
of the tube may enter the sac at one side of one of the synergide, in 
1£. g., Flemming’s triple stain, 
