TIIK FUNGI. 129 



the spores have been completely set free, a ringlike pro- 

 jection around the base of the columella may be seen. 

 This is the collar. 



3. Run iodine solution under the cover glass. The 

 protoplasmic cell contents are slightly stained, the cell 

 wall is not affected, no blue color of the starch reaction 

 is seen, but some spots of a brownish color show the pres- 

 ence of glycogen a substance closely related to starch. 



4. Treat another mount of the hyphse with one per cent 

 osmic acid. Granules in the protoplasm turn brown, 

 showing the presence of oil. 



5. Run Schultze's solution under the cover glass of a 

 fresh specimen and examine the cell wall. The cell wall 

 is stained violet. Is it composed of ordinary cellulose or 

 fungous cellulose ? 



6. Make hanging-drop cultures of the spores. Cement 

 rings of gutta percha or metal to glass slips to serve as 

 culture chambers. Smear the tops of the rings with vase- 

 line. Now place drops of Pasteur's solution, or of the 

 rich juice made by stewing apricots in water and sugar, 

 on the centers of cover glasses. Sow spores of Mucor in 

 these drops. Invert the cover glasses carefully over the 

 rings and press them down into the vaseline, thus forming 

 air-tight, moist chambers. Set aside in warm places and 

 examine from day to day to watch the development of 

 the spores. Make drawings, showing the development at 

 successive stages. 



7. Place a piece of bread bearing a healthy growth of 

 Mucor in a position where the light is equally strong on 

 all sides. Observe after a time that the aerial hyphse 

 grow straight upwards ; they are negatively geotropic. 

 Observe that the root hyphge groAV downwards ; they 

 are positively geotropic. 



8. Place a healthy growth of Mucor in a position where 

 the light is much stronger on one side. After a time 



CLARK'S BOX. 9 



