MOULD FUNGI 93 



production is never through motile zoospores, but through immotile 

 spores produced in sporangia borne at the tips of the reproductive 

 hyphae known as sporangiophores, or by means of conidiospores, 

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

 reproduction is by the conjugation of two similar or sHghtly dissimilar 

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

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

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

 series of transition forms from those like Mucor 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 (sporangioles, 

 microsporangia) and Thamnidium chcetocladioides (Fig. 32), where the 

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

 phore, to Chcetodadium, 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 Piptocephalis, 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 homothallic (mon- 

 oecious) and the heterothallic (dioecious) forms. The homothallic 

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

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

 which two distinct mycelia contribute the gametes which ultimately 

 unite sexually. The homothallic (hermaphroditic) moulds he divides 

 into the heterogamic hermaphrodites in which there is an inequahty in 

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

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

 equal size. The heterogamic hermaphrodites include the following 

 fungi : Syncephalis, Dicranophora fulva, A bsidia spinosa, Zygorhynchus 

 heterogamiis, Z. Mcelleri, Z. Vuillemini. The homogamic hermaph- 

 rodites comprise: Mortierella polycephala, Mucor genevensis, Spinel! us 

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



