8 ELEMENTARY BIOLOGY. [CHAP. 



4. Burst the stained cells by placing a few folds of 

 blotting paper on the surface of the cover-glass and 

 pressing smartly with the handle of a mounted 

 needle: note the torn empty and colourless, but 

 solid and uncrushed transparent sacs ; the soft 

 crushed stained protoplasm. 



5. Repeat observation 3, running in iodine solution 

 instead of magenta. The protoplasm stains brown; 

 the rest of the cell remains unstained. Note the 

 absence of any blue coloration; starch is therefore 

 not present. 



6. Treat another specimen with potash solution, running 

 it in as before : this reagent dissolves out the proto- 

 plasm, leaving the sac unaltered. 



7. [Sow a few yeast-cells in Pasteur's solution in a moist 

 chamber and keep them under observation from day to 

 day ; watch their growth and multiplication.] 



8. [Endogenous division : take some dry German yeast ; 

 suspend it in water and shake so as to wash it. Let 

 the mixture stand for half an hour : pour off the super- 

 natant fluid, and, with a camel's hair pencil, spread out 

 the creamy deposit in a thin layer on fresh cut potato 

 slices or on a plate of plaster of Paris, and place with 

 wet blotting paper under a bell-jar: examine from day 

 to day with a very high power (800 diam.) for asco- 

 spores, which will probably be found on the eighth or 

 ninth day.] 



B. PHYSIOLOGY. 



(Conditions and results of the vital activity of Torula.) 

 i . Sow a fair-sized drop of yeast in 



a. Distilled water. 



b. 10 per cent, solution of sugar in water. 



c. Pasteur's fluid without the sugar. 



