338 



FUNGI 



one gamete is about half the height, though of the same breadth, as the 

 other, the suspensor of the smaller one becomes greatly enlarged after 

 conjugation, while the other remains as it was. In most cases the sus- 

 pensors eventually decay, but in others (Phycomyces, Kze., and Absidia, 

 Van Tiegh.) an outgrowth of darkly coloured hyph^e takes place from 

 each suspensor and invests the zygosperm. In Mortierella (Coemans), 

 which has a smooth extine, this outgrowth arises from the hyphae bearing 

 the suspensors (as well as from the suspensors in one case), and forms a 

 compact integument of the zygosperm. In M. nigrescens (Van Tiegh.) 

 this outgrowth begins after conjugation, first from the suspensors, then 

 from the adjoining hyphce; while in M. Rostafinskii (Bref.) the outgrowth 



Fig. 294. — Rhizopus nigricans YLhr. Formation of a zygosperm. Stages according to 



l;tters (x about 90). (After de Bary.) 



takes place solely from the adjoining hyphse, and begins so early that an 

 investment is formed before actual conjugation takes place. 



A phenomenon resembling that of the parthenogenesis of the Sapro- 

 legnieas is exhibited by a number of the Mucorese in the formation oiazygo- 

 sperms. This occurs in Absidia, Sporodinia (Link), and Spinellus fusiger 

 (Van Tiegh.), and the formation of these bodies ensues when gametes 

 have failed to conjugate, and even when single gametes only are pro- 

 duced. They possess the structure and power of germination of normal 

 zygosperms, just as the parthenogenetic oosperms of Saprolegnia do. 

 Bainier states that Mucor tenuis (Link) forms only azygosperms, and 

 de Bary suggests that the (as yet little known) Azygites of Fries may be 

 found to exhibit this phenomenon. 



On the germination of the zygosperm, as has been said, 2^ proniycele 

 bearing sporanges is produced directly, and these sporanges have the 



