BLAKESLEE. — SEXUAL REPRODUCTION IN THE MUCORINEAE. 229 



Phycomyces nitens Kunze. 



Van Tieghem and Le Monnier ('73j were the first to report the zygo- 

 spores of this species. There is no evidence in the text which would 

 decide the thallic condition of this species, but Phite XX, Figure 4, shows 

 z^'gophores arising from the same hyplia, and it is on the strength of this 

 figure that de Bary ('84, p. 159) classifies Phycomyces with Sporodinia 

 as having zygospores, the progametes of which arise from hyphae organ- 

 ically closely connected, in distinction from Rhizopus and Piptoceph- 

 alis. Van Tieghem's first cultures of Phycomyces were from cochineal 

 from a certain lacquer factory. These died during his vacation, and the 

 cochineal from the same factory had become sterile, but later he obtained 

 cultures from horse dung, and again from cochineal. In obtaining the 

 zygospores it is probable that a transfer from the horse dung was sown 

 on cochineal which already contained the spores of another conjugative 

 strain, since no mention is made of sterilizing the cochineal. Cell cul- 

 tures, presumably from a single spore or from a few spores from a single 

 sporangium, never gave zygospores ; nor w'ere gross cultures of fruits 

 successful, probably either because they were sterilized, or if not, because 

 they failed to contain spores of an opposing strain. 



Bainier ('82) has many times obtained the zygospores upon horse 

 dung mixed with flaxseed flour or soaked with oil. But he adds that 

 often his experiments have not given the expected results. The same 

 author subsequently remarks ('83"', p. 343), that if during February and 

 March a layer of fresh horse dung 5 to 6 cm. thick in a rather large 

 crystallizing dish is sown with Phycomyces, one obtains the zygospores 

 in abundance after ten to fifteen days or more, according to the rich- 

 ness of the sowing. He has many times repeated this experiment, and 

 has always succeeded during the months indicated. Phycomyces with 

 its zygospores has been distributed by Bainier in Rumeguere, Fungi 

 Gallici 4645; see note in Rev. Myc, x. p. 188. 



Although Phycomyces is not uncommon in laboratory cultures, the 

 zygospores have not been reported from this country. Professor 

 Thaxter found them, however, in 1898 in a culture of rabbit dung from 

 Daytona, Florida, and the writer has obtained them synthetically from 

 the two sexual strains (cf. Plate IV). 



The species is typically heterothallic. 



Phycomyces microsporus van Tieghem. 

 A single zygospore of this form was found by van Tieghem ('75) on 

 horse dung, and from the sporangium to which it gave rise further cul- 



