LITERATURE CITED 91 



Stratum by numerous rhizoids. In Rhipidium the sporangium 

 discharges its zoospores into a vesicle. Sexual reproduction in 

 Rhipidium is not unlike that in Sapromyces. Fertilization in R. 

 europaeimi has been studied by Behrens (1931), who reports 

 the formation of a definite exospore from the periplasm. In 

 Araiospora there mav be indications of a vesicle, but when 

 formed it is ephemeral. In this genus two kinds of sporangia are 

 present, one smooth-walled, the other provided with conspicuous 

 spines. In A. pidchra, according to King (1903), the nuclei of 

 the periplasm do not degenerate but become enclosed within cell 

 walls, so that a layer of cells comes to surround the oospore 

 ^\•ithin the oogonium. 



Although possessing a superficial resemblance to the Blasto- 

 cladiales, the arbusculate representatives of the Leptomitales can- 

 not be considered as closely related to that group because of 

 differences in- the structure of the zoospores and composition of 

 the cell wall. They perhaps form an ascending series from such 

 a filamentous form as Apodachlya to the Pythiales or Perono- 

 sporales, which they resemble closely in the structure of sexual 

 reproductive organs. 



LITERATURE CITED 



Behrens, A., "Zytologische Untersuchungen an Rhipidhmi eiiropaeum 

 (Cornu) von' Alinden," Planta, UilV^-lll, 1931. 



Bishop, H., "A study of sexuality in Sapromyces Reinschii," MycoL, 32: 

 505-529, 1940. 



IxDOH, H., "Studies on the Japanese aquatic fungi. I. On Apodachlyella 

 completa, sp. nov., with revision of the Leptomitaceae," Science Repts. 

 Tokyo Bwirika Daigaku, B, ^: 43-50, 1939. 



Kanouse, B. B., "On the distribution of the water molds, with notes on 

 the occurrence in Michigan of members of the Leptomitaceae and Blas- 

 tocladiaceae," Papers Mich. Acad. Sci. Arts Letters, S: 105-114, 1925. 

 "A monographic study of special groups of the water molds. II. Lep- 

 tomitaceae and Pythiomorphaceae," Am. J. Botany, 14:3^5-357, 1927. 



Kevorkian, A. G., "Studies in the Leptomitaceae. II. Cytology of Apo- 

 dachlya brachynenia and Saproviyces Reinschii,'^ My col., 21: 274-285, 

 1935. 



King, C, "Observations on the cytology of Araiospora pidchra Thaxter," 

 Proc. Boston Soc. Nat. Hist.,' 31:2X1-2^5, 1903. 



ScHADE, A. L., "The nutrition of Leptomitus," An?. J. Botany, 27:376-384, 

 1940. 



ScHADE, A. L., AND K. V. Thi.mann, "The metabolism of the water mold, 

 Leptoviitiis lacteiis,^'' Am. J. Botany, 21: 659-670, 1940. 



