8 BOTANICAL GAZETTE [july 



These often appear to be oriented on a point on the nuclear mem- 

 brane, as Olive has found (22), but the presence of a central body 

 was not ascertained with certainty. The hyphae branch monopo- 

 dially at irregular intervals. The branch usually arises in the 

 lateral wall near the apical end of the cell. 



Binucleated cells were sometimes found in the vegetative myce- 

 lium, and continuous filaments of these were found in some cases. 

 It is probable that the sporophytic mycelium had already estab- 

 lished itself, and that both gametophytic and sporophytic mycelia 

 were associated together in the same leaf tissue. 



The aecidia are hypophyllous, and the first evidence of their 

 formation is found in a conspicuous massing of hyphae between the 

 lower epidermis and the cells of the first, second, and third layers 

 of the mesophyll. The center of the young hyphal mass lies be- 

 tween the first and second cell layers. The hyphae are conspicuous 

 on either side of this center for a distance of about two host cells. 

 Thus the area to be occupied includes, in cross-section, 12 host cells, 

 4 cells broad and 3 cells deep. These host cells are gradually 

 destroyed and replaced by the fungous hyphae. 



The host cells in the center of the area are the first to disappear. 

 The hyphae ramify between them, force them apart, and multiply 

 in the intercellular spaces. They act as a wedge between the layers 



them 



ermis 



com 



diminish in size, and in most cases com 



disappear eventually. The hyphae do not penetrate the host cells 



seems 



the 



of the fungous mass. Their walls become much convoluted and 

 infolded. The host cells are not always completely destroyed; 

 sometimes they may be found imbedded in the tissue of an old 

 aecidium. 



In order that they may be described more clearly, the different 

 surfaces of the hyphal mass will be designated as apical, basal, and 

 lateral surfaces, the apical surface being that adjacent to the epider- 

 mis. This will apply to either an epiphyllous or hypophyllous 

 aecidium. The individual filaments that make up the young 



