Ill] 



PLECTASCALES 



6i 



W. decolorans has been identified by van der Wolk as the cause of "yellow 

 grains," a serious disease of stored rice which is endemic in the East Indies 

 and elsewhere, but is prevented by attention to thoroughly dry conditions. 



The only known species of Dipodascus, D. albidus, was discovered by de 

 Lagerheim in Quinto in 1892 on the gummy secretion of Puya, one of the 

 Bromeliaceae. It was found again in 1901 by Juel, in Sweden, on the sap 

 of an injured birch, and has been described by both these investigators and 

 by Dangeard. The mycelium consists of multinucleate cells; it may break 

 up to form oidia and may produce many-spored asci. 



In the initiation of the ascus two branches grow up from the same or 

 different hyphae and fuse at their apices (fig. 22). Both are multinucleate; 

 one is rather larger than the 

 other and continues its growth 

 after fertilization to form the 

 single ascus. Soon after the 

 fusion of the sexual cells one 

 of the nuclei in each is recog- 

 nizable as larger than its neigh- 

 bours. These two nuclei unite, 

 usually in the larger cell, while 

 the rest of the nuclei degenerate. 

 The fusion nucleus passes up 

 into the developing ascus, 

 undergoes several divisionsand 

 eventually gives rise to the nu- 

 clei of the spores (fig. 23). 



Dipodascus differs from Eremascus and the other Endomycetaceae in the 

 presence of accessory nuclei in its gametangia, and from all except Wolkia, 

 in the formation of numerous spores in its ascus. In spite of these differences 

 the resemblance seems sufficiently close to permit its inclusion in the same 

 group. 



ENDOMYCETACEAE: BIBLIOGRAPHY 



1883 ElDAM, E. Zur Kenntniss der Entwickelung bei den Ascomyceten. Cohn's Beitrage 



zur Biol, der Pflanzen, iii, p. 385. 

 1892 DE Lagerheim, G. Dipodascics albidus eine neue geschlechtliche Hemiascee. 



Jahrb. fiir. wiss. Bot. -xxiv, p. 549 

 1902 Juel, H. O. tjber Zellinhalt, Befruchtung und Sporenbildung bei Dipodascus. 



Flora, xci, p. 47. 

 1907 Dangeard, P. A. Recherches sur le developpement du pdrith^ce chez les Ascomy- 



c^tes. Le Botaniste, x, p. 30. 

 1907 Stoppel, R. Eremascus fertilis, nov. spec. Flora, xcvii, p. 332. 

 1909 GuiLLIERMOND, A. Recherches cytologiques et taxonomiques sur les Endomyce- 



tac^es. Rev. G&. de Bot xxi, p. i. 



Fig. 23. 



Dipodascus albidus Lagerh. ; development of 

 ascus and ascospores ; after Juel. 



