GEEEN SLIME 39 



brusli a thin layer of yeast taken from a sup- 

 ply which is actively growing. Put the slab 

 under a bell-jar or a tumbler with some pieces 

 of wet blotting-paper to keep the air moist. 

 With the point of a penknife or scalpel remove 

 some of the cells each day for eight to fourteen 

 days, and examine under the high power of the 

 microscope for spores formed inside the cell. It 

 is well to make several such cultures, as some 

 are almost certain to be spoiled by the growth 

 of moulds and bacteria. Compare with the 

 process of budding. Do you find any relation 

 existing between nutrition and reproduction? 

 Do you find any evidence of the conjugation 

 of individual plants ? 

 Make drawings illustrating endogenous spore-forma- 

 tions. 



General Questions. — Compare the results obtained in 

 all of your work on this plant, and tell what yeast 

 forms from its food. 



Of what use is yeast in bread-making? In brewing? 

 Is yeast a " cultivated plant " ? If so, how is it culti- 

 vated and what is the " soil " upon which it grows ? 



Example 3. — Green Slime {Protococcus Sp.) 



Matenal. — Specimens of green slime, or of other uni- 

 cellular green plants which are so closely related to the 

 form selected as to be equally serviceable, may be found 

 almost everywhere, forming a greenish, slimy ooze on 

 the surface of the mud and stones in the bottoms of 

 slow- running ditches, on the trunks of trees near the 

 ground, on the stones or bricks in the foundations of 



