218 BOTANICAL GAZETTE [march 



The hairs do not branch and seldom consist of more than two cell 

 which are sometimes empty and sometimes filled with a deeply 



epidermal 



sporangium is com 



The 



the epidermis, the tapetum, and the intervening wall layers, 

 epidermis, which is thicker in the upper half of the sporangium than 

 in the lower, consists of thick-walled cells with rather scanty proto- 

 plasm, but with an abundance of suberin and tannin. The tapetum, 

 in comparison with the size of the sporangium, is very insignificant, 

 consisting of a single layer of small cells, with occasional patches two 

 cells in thickness {-fig. 5). The portion of the sporangium wall facing 



sorus 



opposite portions, there being four or five layers of cells between the 

 tapetum and epidermis in the former case, while in the latter there 



ayers {-fig. 4) . The structure of the sporan- 



dermis 



fig 



MICROSPORE MOTHER CELLS 



The microspore mother cells of Dioon present some peculiaritu 

 which are worthy of mention. Upon becoming dissociated 

 seldom assume the usual spherical contour, but remain more 



_ l 1 _ • • 



les 



Lgul 



The chromatin is abun- 



In 



dant, but not always well defined, and it is not unusual for the entire 

 nucleus to stain a dense homogeneous black with iron alum hematox 

 ylin, as if chromatin had gone into solution in the nuclear sap. 

 such cases, there are in the cytoplasm irregular masses of similarly 

 - staining material which take the spherical form and begin to resemble 

 nucleoli as the homogeneous staining of the nucleus ceases and the 

 chromatin becomes definitelv mitKnoH wrhm these spherical bodies 



jd. When 



made to o 

 blepharoplast, but it was easily determined that they were 



L A ■* * _ m 



surrounded by radiations. 



masses 



true 



vary 



jrmed 

 never 



1. but 



While 



masses was 



~t«w*,m a puruon 01 me deeply .staining materia] 

 from the interior of the nucleus into the cytoplasm. 



terial which has pa 



V. 



sed 



