6o THE SAPROLEGXIACEAE 



13. Saprolegnia hypogyna Pringsheim. Jahrb. f. wiss. Bot. 9: 191, pi. 

 18, figs. 5, 9, 10. 1873. 

 Saprolegnia intermedia Maurizio. Jahrb. f. wiss. Bot. 29: 97, pi. 2, 

 figs. 37-5 1 a. 1896. 



First described briefly by Pringsheim as a variety of S. Jerax (but 

 referred to as 5. hypogyna in the description of the figures), this plant 

 was later recognized as a species by deBary (Bot. Zeit. 46: 615. 1888). 

 It is defined by Pringsheim and deBary as having no antheridial 

 branches, but with an antheridial cell cut off, usually just below the 

 oogonium, from which an antheridial tube pushes up through the wall in 

 most cases. As e\en the more typical Michigan form departs in certain 

 respects from the European, we add below deBary 's description for com- 

 parison : 



"Threads delicate, strict; primary sporangia repeatedly proliferating 

 from within. Oogonia terminal and then mostly round or pear-shaped, 

 or intercalary and then broadly barrel-shaped, not rarely two or more 

 in a row; wall smooth, moderately thick, with not very numerous large 

 pits. Egg usually about 5-10 (1-40), centric as in 5. monoica. Anther- 

 idial branches absent ; antheridia usually present in the form of a cylindrical 

 or clavate-cjdindrical cell, which is cut off just below the oogonium; an- 

 theridial tubes usually entering the oogonia through the basal wall, often 

 branched and not rarely absent. Intercalary oogonia when single fre- 

 quently have an antheridium cut off at each end with antheridial tubes 

 present or absent. A small proportion of the oogonia remain without 

 antheridia even to full maturity of the eggs." 



A form of this species approaching the typical has been found in 

 America heretofore only by Kauffman in Michigan (Ann. Bot. 22: 361, 

 pi. 23. 1908. Also noted in Ann. Rep. Mich. Acad. Sci. 8: 27. 1905). 

 He does not describe in detail the normal appearance of his plant on 

 insects in pure water, but as he does not mention the absence of the 

 suboogonial cell in such conditions it is to be presumed that it is regu- 

 larly present. In a set of experiments with haemoglobin or peptone 

 with or without the addition of various salts Kauffman found that in 

 case oogonia were produced the antheridial cell was always present in 

 most of the media, and partly absent in a few. Side branches from 

 the antheridial cell were often present, and attached themselves to the 

 oogonium abo\'e. In KaPOj and to a less extent in KNO, and Na.HPO. 

 the normal behavior could be so modified that there were formed numer- 

 ous antheridial branches, mostly of diclinous origin, much as in 5. mixta 

 and S. diclina. Several of Kauffman's drawings (figs. 5, 6, 7, 14, 15 and 

 16) show androgynous antheridial branches running up around the 

 oogonium from immediately below it, as in var. Ill of Maurizio (see 

 below). These two forms, therefore, approach nearest to A planes Treleas- 



