saproli:gnia 49 



oogonial stalks. The oogonia were heavily pitted, about 35.5XIo8.5;a 

 thick; the eggs up to 40, with a diameter of 22.5-27.5;j.. 



In his pioneer work on the response to various media in tliis group 

 Klebs studied a plant that he regarded as S. mixta, although on a natural 

 substratum, as flies in water, it produced constantly only 10-20% of 

 oogonia with antheridia. For a summary of his important results see 

 under 5. ferax, where, according to our rule, it is to be presumed that 

 Klebs 's strain should be placed. For experiments on the behaxior of the 

 spores of 5. mixta under various chemical stimuli see MuUer ('n). 



Saproleguia heterandra Maurizio is so near S. mixta as to be best treated 

 as a form of it, although Maurizio places it nearest 5. tondosa. It may 

 be briefly described as follows: Antheridia on about half the oogonia, 

 androgynous or diclinous. Eggs 23.5-28;x in diameter, 1-40 in an oogo- 

 nium, usually 4-10; germinating in 60 days by a short germ tube; oogo- 

 nia arranged very variously but not in chains; pits not numerous and 

 of medium size. 



According to Humphrey, what Schroeter ('89) took to be 5. Jerax is 

 more like his (Humphrey's) S. mixta. In such case S. dioica Schroeter 

 ('69, p. 143), listed without description, is also S. mixta, as Schroeter 

 later ('89) quotes it as a synonym of his S. Jerax. 



7. Saprolegnia monoica Pringsheim. Jahrl). f. wiss. Bot. 1: 2()2, pis. 

 19 and 20. 1858. 



? S. dioica Pringsh. Jahrb. f. wiss. Bot. 2: 266. i860. (This 

 may be 5. ferax. See Fischer ('93), p. 336.) 



Achlya intermedia Bail. Xaturf-\'er. Konigsb.. p. 5. 1861. 



Diplaties saprolegnioides Leitgeb. Jahrb. f. wiss. Bot. 7: 374, pi. 

 24. 1869. 



Saprolegnia semidioica Petersen. Bot. Tidssk. 29: 378. 1909; also 

 Ann. Myc. 8: 519. 1910. 



The typical form of this species as understood by European botan- 

 ists has not been recognized in any of our collections, and its presence 

 in America is somewhat doubtful. The form reported by Humphrey 

 seems to l)c the \ar. glomerata, and it does not appear what form .Atkinson 

 had from Alabama. We include the species as .American from the Michigan 

 recordbyPieters(Mycologia7: 307, pi. 170, fig. 2. 1915; also listed in Ann. 

 Mich. Acad. Sci. 17 : 195. 1915) who, while he does not gi\-e the necessary data 

 to determine his form, does show in his drawing an oogonium with at least 

 eight eggs which by measuring and reducing to scale seem to be about 15- 

 18,1 thick, a size in accordance with the type as understood by F"ischer. 



Pietcrs has shown ('15a, p. 312) that in 0.05% haemoglobin the num- 

 ber of oogonia with antheridia is reduced to o-i ^%. For other experiments 



