WITH NOTES OX OTHER SPECIES. 101 



tions, and showed the necessity for characters drawn from the sexual organs in spe- 

 cific determinations. It is to him and to subsequent writers who recognized the cor- 

 rectness of his position, that we owe our present notions of generic and specific 

 distinctions. No writer before him appreciated the true specific difierences, and none 

 save !N^ees, whose insight remained unrecognized for three decades, saw the true value 

 of characters now recognized as generic. With the single exception of Thuret's S. 

 ferax, no species had previously been described or figured so as to be now recog- 

 nizable. It is an interesting coincidence that his first botanical publication and the 

 posthumous fragment prepaied from his last manuscripts by his successor should 

 both have dealt with Saprolegniacece. 



The history of the great progress in the knowledge of this family during the 

 past forty years may be traced, as has been said, in the works referred to on other 

 pages ; but certain matters which are now wholly of historical interest may be briefly 

 referred to here. The discussions concerning the specific value of certain morpholog- 

 ical differences and concerning the sexuality of these fungi are considered suffi- 

 ciently elsewhere. But the members of this family have figured prominently in the 

 pleomorphy craze which followed Tulasne's proof of the pleomorphism of many Asco- 

 mycetes. The extreme advocates of this doctrine. Bail ('60), Hoff'man ('67), and 

 Ivarsten ('69), held that the same plant assumes the form of Saprolegnia in water, or 

 of Empiisa in air, when growing on flies. On other substances the same species was 

 supposed to appear as Mucoi\ or even as Penicillium ; and in saccharine solutions to 

 take the Saccharomyces form. Earlier than these views became popular, similar sug- 

 gestions had been made. !N^ees ('31) suggested a connection between Empusa and 

 Aclilya; and Meyen and Cienkowski ('55) affirmed a connection between Isaria or 

 Empusa, on one hand, with ^^AcJdya prolifera,^^ on the other. It is to Brefeld's 

 researches ('71) and the application of rigid culture methods like his that we owe 

 the final proof of the incorrectness of this belief. 



The history of American studies of Saprolegniacece, is briefiy told. So far as I 

 know, Leidy ('50) first mentioned ''^Aclilya prolifera,^^ which he reported having seen 

 in all stages of development on Ascarids in water. Gerard's ('78) brief account of 

 " S. ferax ^' in connection with an epizootic among fish in I^ew Jersey, Hine's ('78) 

 observations on a species of Saprolegnia and on Aclilya raceniosa, and Galloway's 

 ('91) cytological notes on S. monoica complete the short list. 



Systematic Part. 



The following diagnoses of American species of SaprolegfiiaCece are drawn wholly 

 from American specimens, except in a very few cases where the incompleteness of 



