LITERATURE CITED 97 



formed may vary considerably within a single species. As many 

 as thirty eggs may be formed in certain species. 



The development of the antheridiiim, paralleling that of the 

 oogonium, culminates in the formation of fertilization tubes, 

 which penetrate the oogonial wall and enter the eggs. Fertihza- 

 tion has been demonstrated in a considerable number of species 

 of Achlya [Patterson (1927), Wolf (1938)], Saprolegnia [Claus- 

 sen (1908), Hohnk (1935a)], Aphanomyces [Kasanowsky 

 (1911)], Brevilegnia [Cooper (1929)], Leptolegnia [Couch 

 (1932)], and Thraustotheca [Shanor (1937)], and doubtless it 

 occurs whenever antheridia are present. It has been known since 

 the time of de Bary that antheridia may not be present on all the 

 oogonia produced, and in certain forms oospores may be pro- 

 duced parthenogenetically. 



The mature oospore is surrounded by a heavy wall. After a 

 rest period of several months, the oospore eventually germinates 

 by forming a short germ tube bearing a sporangium. It has re- 

 cently been shown [Schrader (1938)] that meiosis occurs dur- 

 ing oospore germination. 



LITERATURE CITED 



Claussen, p., "Uber Eientwickelung und Befruchtung bei Saprolegnia mo- 



noica^'' Ber. dent, botmi. Ges., 26: 144—161, 1908. 

 CoKER, W. C, The Saprolegniaceae, with notes on other ivater molds. 201 



pp. University of North Carolina Press, Chapel Hill. 1923. 

 "Other water molds from the soil," /. Elisha Mitchell Sci. Soc, 42: 207- 



226, 1927. 

 CoKER, W. C, AND V. D. Matthews, "Saprolegniales (Saprolegniaceae, Ec- 



trogellaceae, Leptomitaceae)," North Am. Flora, 2, Part 1: 15-67, 1937. 

 Cook, W. R. I., and Enid Morgan, "Some observations on the Saproleg- 

 niaceae of the soils of Wales," /. Botany, 72: 345-349, 1934. 

 Cooper, G. O., "Cvtoiogical studies on the sporange development and 



gametogenesis in Brevilegnia diclina Harvey," Trans. Wis. Acad. Sci.j 



2-^:309-322, 1929. 

 Couch, J. N., "Heterothallism in Dictyuchus, a genus of the water molds," 



Ann. Botany, ^0:849-881, 1926. 

 "The development of the sexual organs in Leptolegnia caudata,^'' Am. J. 



Botany, 19: 584-599, 1932. 

 Drechsler, C, "The beet-water mold and several related root parasites," 



/. Agr. Research, 5<?; 309-361, 1929. 

 Harvey, J. V., "A survey of the water molds occurring in the soils of 



Wisconsin, as studied during the summer of 1926," Trans, Wis. Acad. 



Sci., 23:551-562, 1928. 



