i9o8] YAMANOUCHI— SPERMATOGENESIS AND OOGENESIS 157 



plate being laid dovm so as to divide the cytoplasm into two une 

 cells. The immense amount of food material in the wntral cell ca 

 its nucleus to grow more rapidly than that of the neck canal cell, 

 this time these two nuclei contain 66 or 64 chromosomes. 



At 



more mitosis (simultaneous or successive) in 



each of these cells. The mitosis 



(figs. 43-43)' In the telophase 



er nuclei are formed, a cell plate is la 

 begins to disorganize and finally disappe 



The direction of this mitosis is various, be 



sometimes oblique. 



sometimes perpendicular to it, and 



The 



(figs. 46-48), No peculiarity 

 :he metaphase (fig. 46). when t 



present a single dark staining body near the spindle, which pos- 

 sibly may be a persistent nucleolus, but its origin w^as not traced. 

 The peculiar thread structure of unknown substance which is differ- 

 entiated in the central cell is also continuously obser\-ed in the ventral 

 cell, without any visible connection with the mitotic figure. In the 



o 



marked 



and shape, perhaps due to a nucIeo-c}1;oplasniic relation, similar 

 the case previously obsen"ed {fig. 47). Several nucleoli appear in 1 

 young daughter nucleoli (fig. 48). 



cun^ature of the nucleus of the egg cell begins 



this 



shaped 



ger duration than that between 



the neck canal cells. The egg nucleus grows to an immense size and is 

 ver}' irregular in outliae, w^hereas the neck canal cell and the ventral 

 canal cell collapse and become mucilaginous, together with their 



orcranizin 



FERTILIZATION 



The egg cell w^hen ready for fertilization lies in the bottom of th< 

 archegonial ca\ity. Some of the material resulting from the disor 

 ganization of canal cells remains in the neck and ventral regicm of the 

 archegonium as a slimv sul^tance. even after the wide opening of the 



