100 THE SAPROLEGNIACE^ OF THE UNITED STATES, 



ing his synonymy confusedly. Berkeley ('33) followed Agardh's generic arrange- 

 ment, and called the form he figured Leptomitus piscidlcola. 



After brief and unimportant mention of these plants in earlier papers, Meyen 

 described ('39) some features of the development and escape of the spores and of 

 their germination. He also observed dictyosporangia. ISTow followed a series of 

 accounts of observations concerning the attacks of Saprolegniacex on aquatic Verte- 

 brates by Hannover ('39 and '42), Stilling ('41), Bennett ('41), and Goodsir ('42). 

 These papers contained little of real importance except Hannover's second one, which 

 has been before mentioned as containing the first good account of the development 

 and later history of the zoospores. Unger's account ('43) was in some respects less 

 complete than that of Hannover. All the writers yet mentioned dealt only with the 

 sporangia, in most cases of the Saprolegnia type; but nearly all called their plants 

 Achlya prolifera. In Schleiden's " Grundzlige" ('45), we find the first account of a 

 second and larger sort of spores, which we now know as the oospores. These were 

 again mentioned by !N'aegeli ('47) and by Braun ('51), the latter of whom also 

 described the antheridial branches. Naegeli ('47) speaks of a third sort of reproduc- 

 tive organs, which were probably, like those described by Cienkowski ('55) the 

 sporangia of parasitic Chytridiacece of the genus Olpidiopsis. The general features 

 of the development of both sporangia and oogonia were described at this time by 

 Thuret ('50), who then first demonstrated the biciliate character of the zoospores of 

 Saprolegnia, and figured unmistakably the oogonia of the form he studied, which he 

 called S.ferax. Now followed those accounts by Pringsheim ('51) and DeBary ('52), 

 which mark the beginning of our exact knowledge of the Saprolegniacece, and which 

 have led to the long series of contributions, the most important of which are quoted 

 in the morphological and systematic parts of the present paper. The number of these 

 which we owe neither to the researches nor to the direct influence of these two pio- 

 neers and masters in the study of the Thallophytes is surprisingly small. 



To return to the systematic history of the group : Kiitzing, in his " Phycologia" 

 ('43), places L. ladeuSy with various other forms not Saprolegniaczoe. and largely 

 unidentifiable, under the genus Leptomitus, and includes the other forms then known 

 under three species of Saprolegnia, S. minor, ferax, and xylopliila. In his "Species 

 Algarum " ('49) the same author includes L. lacteus as before, and enumerates six 

 additional species of Saprolegnia, most of which are now unrecognizable. Braun 

 ('50) established the species S. capitulifera for a plant with sporangia of the Achlya 

 type. Robin ('53) mentions only S. minor and S.ferax; and Pringsheim, in his ear- 

 liest paper ('51), though describing a Saprolegnia, calls it A. prolifera. It was 

 DcBary ('52) who first again brought forward and applied I^ees' old generic distinc- 



