MOULD FUNGI 93 



production is never through motile zoospores, but through immotile 

 spores produced in sporangia borne at the tips of the reproductive 

 h)^hae known as sporangiophores, or by means of conidiospores, 

 chlamydospores (Mucor racemosus), oidiospores, or gemmae. Sexual 

 reproduction is by the conjugation of two similar or slightly dissimilar 

 gametes, and the formation of a resting cell, or sexually produced spore, 

 known as the zygote, or zygospore. Brefeld believed that this group 

 gave rise to the higher groups of fungi and he showed an interesting 

 series of transition forms from those like Mticor with a typic terminal 

 sporangium (Fig. 13) with numerous sporangiospores (endospores) 

 through Thamnidium elegans with a large terminal sporangium (mega- 

 sporangium) and secondary lateral smaller sporangia (spwrangioles, 

 microspwrangia) and Thamnidium cfuBtodadioides (Fig. 32), where the 

 absent terminal megasporangium is represented by a spine-Uke sporangi- 

 phore, to ChcRtocladium, where the number of endospores in the spor- 

 angioles is reduced to one inclosed within the sporangium, which be- 

 haves as a conidiospore; thence to Piptocepkalis, where the monosporous 

 sporangiole has become virtually a conidium, or conidiospore. He re- 

 garded the ascus as potentially a sporangium, but recent discoveries 

 have shown this hypothetic view to be untenable, so that his views as 

 to the origin of the ASCOMYCETALES and the BASIDIOMYCE- 

 TALES from the ZYGOMYCETALES must be considered as not satis- 

 factorily proved. 



Blakeslee, who has studied the sexual reproduction in the moulds, 

 finds that they may be divided into two groups, the homothaUic (mon- 

 oecious) and the heterothaUic (dioecious) forms. The homothaUic 

 moulds are those in which the sexual gametes, which conjugate, arise 

 from the same mycelium, while the heterothaUic forms are those in 

 which two distinct myceUa contribute the gametes which ultimately 

 unite sexuaUy. The homothaUic (hermaphroditic) moulds he divides 

 into the heterogamic hermaphrodites in which there is an inequality in 

 the size of the gametes (the large one being female and the smaU one 

 male), and the homogamic hermaphrodites in which the gametes are of 

 equal size. The heterogamic hermaphrodites include the foUowing 

 fungi: Syncephalis, Dicranophora fulva, Absidia spinosa, Zygorhynchus 

 heterogamus, Z. Modleri, Z. Vuillemini. The homogamic hermaph- 

 rodites comprise: Mortierella polycephala, Mucor genevensis, Spinellus 

 fusiger and Sporodinia grandis (Fig. 28). The dioecious, or hetero- 



