BLAKESLEE. — SEXUAL REPRODUCTION IN THE MUGORINEAE. 243 



SO narrow (1-2/x diam.) that connections can be made out with great 

 diflBculty and only by use of stains. In speaking of the zygophoric 

 hyphae he remarks : " In spite of the intricate twisting of the hyphae 

 they can in every case be followed in different directions and belong 

 to different threads of the mycelium." This fact, added to Brefeld's 

 inconstant results with sporangial sowings ('81, p. 75), renders a hetero- 

 thallic condition probable. 



Spegazzini ('91) mentions zygospores in his redescription of this 

 species under the name of P. arrkiza. 



Pitocephalis Tieghemiana Matrucliot. 



Matruchot ('99) found this form growing on Rhizopus nigricans which 

 had developed upon germinating seeds of pea^, bean, etc. This is its 

 only reported occurrence, and neither the description nor the figures give 

 us any evidence as to the thallic condition. 



In 1896 Professor Thaxter found a Piptocephalis with zygospores 

 growing in a bread culture from Mammoth Cave, Ky. In the position 

 of suspensor attachments the form resembles P. Freseniana, but the 

 zygospores are quite distinct from those figured by Brefeld. Another 

 form found by him in the same year on a Mucor-infected Myxomycete 

 from Kittery Point, Me., has zygospores whose suspensors are attached 

 at consideralile distance from each other, and thus resemble those of 

 P. Ttegheimana^ but the species differs somewhat from Matruchot's 

 description. The writer has examined preparations of these two forms 

 and finds the hyphae connected with the suspensors to remain separate as 

 far as they can be followed. 



Syncephalis nodosa van Tiegliem. 



In Figures 17 and 19, Bainier (82) shows the conjugative branches 

 arising from the same hypha, and the secondary zygospores are said to 

 be formed from zygophoric branches arising from the same base. 



Thaxter ('97) reports the species as being very common in this coun- 

 try, and remarks that one seldom fails to obtain the zygospores in abun- 

 dance whenever it grows on a copious substratum of other mucors. 

 The figures are negative as regards the origin of the zygophoric hyphae. 



Vuillemin (86'') used the zygospores of this species in his study of the 

 zygosporic membranes. The writer has several times found this species 

 with zygospores, and it has frequently been found in the laboratory with 

 the same form of reproduction since 1887. He has been uuable to con- 



