STRUCTURE. 



51 



but there are points in the structure which can best be alluded 

 to here. Again taking Professor de Bary's researches as our 

 guide,* we will illustrate this by the common Mucor mucedo: 

 If we bring quite fresh horse-dung into a damp confined 

 atmosphere, for example, under a bell-glass, there appears on its 

 surface, after a few days, an immense white mildew. Upright 

 strong filaments of the breadth of a hair raise themselves over 

 the surface, each of them soon shows at its point a round little 

 head, which gradually becomes black, and a closer examination 

 shows us that in all principal points it perfectly agrees with 

 the sporangia of other species. 

 Each of these white filaments 

 is a sporangia-bearer. They 

 spring from a mycelium which 

 is spread in the dung, and 

 appear singly upon it. Cer- 

 tain peculiarities in the form 

 of the sporangium, and the 

 little long cylindrical spores, 

 which, when examined sepa- 

 rately, are quite flat and co- 

 lourless, are characteristic of 

 the species. If the latter be 

 sown in a suitable medium, 

 for example, in a solution of 



sugar, they swell, and shoot 



FIG. 31. Mucnr mucedo, with three sporangia. 

 . Portion of frill with sporaugiola. 



forth germinating utricles, which quickly grow to mycelia, which 

 bear sporangia. This is easily produced on the most various 

 organic bodies, and Mucor mucedo is therefore found sponta- 

 neously on every substratum which is capable of nourishing 

 mildew, but on the above-named the most perfect and exuberant 

 specimens are generally to be found. The sporangia-bearers 

 are at first always branchless and without partitions. After 

 the sporangium is ripe, cross partitions in irregular order and 

 number often appear in the inner space, and on the upper 



* De Bary, "On Mildew and Fermentation, "in "Quarterly German Magazine," 

 or 1872. 



