152 BOTANICAL GAZETTE [march 



:perficial cells 



may 



in the central cell. It does not seem 

 the nuclear division. As successive mitoses proceed, it becomes 

 more faintly stained, less conspicuous, and finally becomes impossible 

 to differentiate by staining; but in rare cases it still remains, filling the 

 whole cyioplasm up to the eight- or sixteen-cell stage of the sperma- 

 togcnous cells. A structure of similar appearance was observed in 

 the central cell of the archegonium {figs. 41, 41a). 



The spermatid mother cell is characterized by the first appearance 

 of blepharoplasts. In general, the spermatogenous cells, in spite of 

 their small size compared with the vegetative cells of the prothallia, 

 contain large nuclei. The cytor 



asm seems 



delicate. 



ery fine fibrillar structure, and the membrant 



Jes which take place in the spermatogenous c( 



accoimt of the comoarativelv larsre amount 



chromatin, but otherwise they resemble those of the vegetative cells. 



In the telophase of the mitosis, previous to the formation of the 



spermatid mother cell, the groups of daughter chromosomes, having 



reached the poles, begin to be vacuolized. Detailed study of this 



v-acuolized chromoso 



me 



appears concave from the side view {fig. 



The nucleus when viewed from the pole shows that the chromatin 

 material resulting from the vacuolized chromosomes is very scanty 

 m the polar region and three or four nucleoli are always present 

 {figs. 12, ij) ; such a structure of the nucleus may be regarded as a 

 kmd of polarity. If there could possibly be any migration of nucleoli 



occur 



mtenor of the nucleus to the cytopi 



able any peculiar differentiation within the cytoplasm that might 

 warrant the supposition. 



As the young daughter nucleus grows in size and assumes a spheri- 

 cal form, the chromatin loses its peculiar arrangement and becomes 

 transformed into the irregular ragged reticulum of the resting condi- 



""ii C"^"^ ^^^"^ ^""^ observ-ed by their differential staining two 

 smaU bodies, the primordia of the blepharoolasts. Ivinff within the 



