KICHAEDS. — DEVELOPMENT OF ^CIDIA. 255 



xiy. 



CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORATORY 

 OF HARVARD UNIVERSITY. 



XXXIV. — ON SOME POINTS IN THE DEVELOPMENT 

 OF ^CIDIA. 



By Herbert Maule Richards. 



Presented by T. W. Richards, November 13, 1895. 



Very little has beea published in the last twenty years regarding 

 the development of the a3cidium stage of the UrediueiE, and very 

 little more is known than at the time when De Bary * wrote his text- 

 book. Very recently Neumann t has given an account of the develop- 

 ment of the a^cidium, but his researches do not throw a great deal 

 of light on the question. He is able to trace the origin of the basidia, 

 or foot cells, as he calls them, only in a very general way, and as 

 regards disputed points as to the formation of the peridium and the 

 growth of the hymeniura there is much to be said. Other authors 

 have considered the question of the sexuality of the fecidium, but 

 hardly any of them have taken it up from the developmental stand- 

 point of the organ itself. Reference will be found to these papers 

 in a genei'al discussion at the end of this article. 



In obtaining material for the study of the development of the 

 cecidium it is necessary to consider several things. Not only must the 

 material be plentiful, but the a^cidium had best be a large one, and, 

 above all, the tissues of the host of such a character as to allow of suc- 

 cessful manipulation. For the latter purpose nothing could be better 

 than an aquatic host, the tissues of which are usually loose, and the 

 chlorophyll, at least in the more or less submerged portions, not so 

 abundant as to interfere with a clear view of the hyphfe of the fungus. 

 Notliing was found more favorable than an ^Ecidium on Peltandra 

 lui'Iulata, which may be obtained in quantity in the neighborhood of 



* Morphologie der Pilze, 1884. 



t Ueber die Entwickl., der Aecidieii, etc., Hedvvigia, 1894, Heft 6. 



