1914] 



FROMME—AECIDIUM CUP 



13 



in the general appearance of the sorus, than any of the others. The 

 number and position of the gametes are practically the same in 



both. 



com 



compact DseudoDarenchvma 



toniata, and consequently form a more 

 P. Violae is likewise a very favor- 

 able form for study, although the later stages do not fix so favorably 

 as do the earlier ones. 



In general appearance the early development of Ur. Caladii is 

 much unlike that of the two foregoing species. The aecidium is 

 much broader and shallower and is more 

 superficially located in the leaf tissue. The 

 young aecidium has the appearance of a 

 deep-seated caeoma. The perpendicular 

 gametophoric hyphae do not converge to- 

 ward a central point in the young hyphal 

 mass to such a noticeable degree, but run 

 almost vertically toward the epidermis, a 

 condition to be expected in a broad shallow 

 sorus (text fig. 2). This condition of the 

 gametophoric hyphae is more suitable to 

 the study of the individual hyphae, and 

 the sterilization of their apices and the 

 position of the gametes are more easily 

 seen. 



The game 



Fig. 2. — Section through 

 Ophoric hyphae Consist of the young aecidium of Ur. 



about 6 or 7 cells (text fig. 2). The upper ?*** ?' apical surface; > 



r * basal surface ; g, gametic tis- 



3 or 4 of these are sterilized and the remain- sue; Py pseudoparenchyma. 



gametes 



As 



a rule, about two layers of gametes are formed, though in some 

 cases there was apparently only one, and three were sometimes 

 seen. The gametes are especially large at the time of fusion. 

 The sterile cells do not disintegrate very completely prior to the 

 fusions, and consequently scarcely any characteristic pseudopa- 



ma 



appears. The aecidium is favorable for study, since 

 both cells and nuclei are large. In comparing the sections of my 

 material on Arisaema with Richards 7 figures (27, figs. 1-4) of 

 Ur. Caladii on Peltandra, it seems evident that the aecidium on 



