MUCOR MUCEDO. 315 



the rapid development of this fungus, it is well to state that, 

 should we wish to carefully study the various stages as above, 

 it will be necessary to start several similar cultures, since for 

 observation a cover-glass must be laid on, and the preparation 

 will thus be spoiled for further development. With a sufficiently 

 high power, protoplasmic streaming will be readily recognisable, 

 and especially along the wall of the gonidiophore. 



Permanent preparations of spore-cultures, at any time prior 

 to the elongation of the gonidiophore, can be made by fixing the 

 object by carefully flooding the object-slide with one of the fixing 

 fluids, and then staining the object while still upon the slide. In 

 the centre of such a preparation the original gonidium can usually 

 be still recognised as a slight swelling (see Fig. 113*, C). 



Sexual Reproduction of'Mucor. On the object-slide we obtain 

 only gonidiophores, ultimately several on each individual ; in 

 order to see the sexual organs and zygospores (zygotes), we 

 must make a culture en masse. They are most readily obtained 

 upon horse-dung cultures, but rarely in quantity ; so that we 

 often look for them in vain. When present the zygospores show 

 on the dung as black dots. If such a dot be carefully removed 

 to an object-slide, we can, if it be actually a Mucor zygospore, 

 recognise it as a black ball covered with wart-like projections. 

 It is very readily torn, but if it should happen to be complete, we 

 can recognise the two ends of darkly-coloured mycelial threads 

 attached to it (Fig. 114, C). If the mycelial thread be torn off, or 

 has already separated from the zygospore, the places of attachment 

 can be seen as clear circular spots (Fig. 114, D). These can 

 be seen with special ease when the zygospore is crushed. The 

 contents of the zygospore consist, as is then seen, of finely 

 granular protoplasm and oil. Besides the ripe zygospores, we 

 may also find younger, paler, or even colourless ones which 

 do not yet possess the warty prominences ; and we may even 

 have portions of mycelium in which the formation of zygospores 

 has just commenced. We then see two mycelial threads, rich in 

 contents, the ends of which have swollen spherically, which have 

 joined together by their apical surfaces (Fig. 114, A and B). At 

 a little distance from these surfaces each of the swollen ends has 

 been cut off by a partition wall. In somewhat older stages, 

 the contact surfaces of the two sexual organs have disappeared, 

 and the contents of both cells have mingled. The zygospore 

 (zygote), which has thus resulted from the copulation or 



