PHYSIOLOGY. 



Protoplasm in mucor. 



12. Let us now examine in a similar way anotlier of tlie 

 simple plants with the special object in view of demonstrating 

 the protoplasm. For this purpose we may take one of the plants 

 belonging to the group of fungi. These jjlants jiossess no 

 chlorophyll. Ono of several species of miicur, a conmion 

 mould, is readily obtainable, and very suitable for this stLidy.^= 



13. Mycelium of mucor. — A {^\n days after sowing in some 

 gelatinous culture medium we find slender, hyaline threads, which 

 are very much branched, and, radiating from a central point, form 

 circular colonies, if the plant has not been too thickly sown, as 

 shown in fig. 6. These threads of the fungus form the myce- 

 lium. From these characters of the plant, which we can readily 

 see without the aid of a microscope, we note how different it is 

 from spirogyra. 



To examine for protoplasm let us lift carefully a thin block of 

 gelatine containing the nnicor threads, and mount it in water on 

 a glass slip. Under the microscope we see only a small portion 

 of the branched threads. In addition to the absence of chlo- 

 rophyll, which we have already noted, we see that the myce- 

 lium is not divided at short intervals into cells, but appears 

 like a delicate tube with branches, which become successively 

 smaller toward the ends. 



14. Appearance of the protoplasm. — Within the tube-like 

 thread now note the protoplasm. It has the same general ap- 

 pearance as that which we noted in spirogyra. It is slimy, or 

 semi-fluid, partly hyaline, and partly granular, the granules con- 

 sisting of niijuite particles (the microsomes), \\hilc in mucor the 

 protoplasm has the same general appearance as in spirogyra, its 

 arrangement is very different. In the first place it is plainly 



*The most suitable preparations of mucor for study are made bv fjrowiiKr 

 the plant in a nutrient substance wliicli larijcly consists of yclaline. or, lietter, 

 agar-agar, a gelatinous preparation of certain seawce.ls. 'I'liis, after the 

 plant is sown in it, should be poured into sterilized shallow glass plates, 

 called Petrie dishes. 



