RESEARCHES ON THE MUCORINI. 53 



The mycelium of the Mucori7ii always originates from a 

 spore of asexual origin ; the sexually produced spore or zygo- 

 spore never produces mycelium, but developes at once an 

 asexual reproductive apparatus. 



Placed under favorable conditions the asexual spore puts 

 out one or more tubes or hyphse, which elongate and ramify, 

 forming a mycelium, which in the first instance is always 

 unicellular, as in the Peronosporece and Saprolegniacece. 

 The more or less granular protoplasm which the hyphae 

 contain possesses characters different from those met with 

 amongst Ascomycctes and Basidiomycetes. Later on, as the 

 protoplasm disappears from the hyphae, septa, more or less 

 irregularly distributed, make their appearance. Usually the 

 hyphae preserve a complete independence, but in some genera 

 of the family {Ch(Etocladimn, Mortierella, Syncepludis) they 

 form numerous anastomoses. Their meuibrane is always 

 colourless. Tlie mycelium sometimes develops exclusively 

 in the interior of the nutrient medium ; sometimes it de- 

 velops.itself equally both in this medium and in the air. lu 

 some Mucorini it may occasionally attach itself to the 

 mycelium or productive apparatus of other plants of the same 

 family, and derive nutriment from them — in fact, become 

 parasitic {Chcetocladkmi, Piptocejihalis , Syncephalis). But 

 this parasitism appears to be far from essential, since the 

 same mycelium fructifies and vegetates almost equally well 

 when completely isolated. No species of the J/z^conwi appears, 

 therefore, to be parasitic in the fullest and absolute sense of 

 the word. 



Asexual reproduction ; Sporangia. All the Mucorini de- 

 velope from this mycelium erect hyphae, in some cases 

 energetically responding to light {Mucor, Phyconiyces, Sec), 

 in other cases wholly insensible to it {Rhizopus, Circinella) ; 

 their niembrane is coloured blue or, at any rate, violet or 

 rose colour by Schultz's solution, and they terminate 

 in a system of sporangia, in which the asexual spores originate 

 by a process of division. Sometimes these sporangia are 

 globular, and they then usually contain a large number of 

 spores, ranging from 500,000 to \0 {Phyconiyces, Mucor, See). 

 Occasionally the sporangia are uniformly monosporic (CA«e^o- 

 cladiuni). In Piptocephalis and Syncejjhalis the spores are 

 arranged in a narrow sporangium in a single row. The de- 

 hiscence of the sporangium takes place in different ways; its 

 membrane may become totally absorbed without leaving any 

 trace as soon as the spores become mature. A drop of fluid 

 secreted from the apex of the sporangiferous hypha envelope 

 the liberated spores {Mortierella, Piptocephalis, Syncephalis), 



