8 ELEMENTARY BIOLOGY. [l. 



crushed 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 ; 

 Avatch their growth and multiplication.] 



8. [Endogenous division: take some yeast which has been 

 grown in Pasteur's solution at a temperature below 20 C. ; 

 spread it out in a thin layer on fresh cut potato slices or on 

 some 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 ascospores, which will probably 

 be found on the fifth or sixth day.] 



B. PHYSIOLOGY. 



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

 1. 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. 



d. Pasteur's fluid with sugar, 

 [c?. Mayer's pepsin solution 1 .] 



1 Mayer's solution (with pepsin) = 



15 per cent, solution of sugar-candy 20 cc. 



Dihy dropotassic phosphate o- 1 grm . 



Calcic phosphate cri grm. 



Magnesic sulphate o*igrm. 



Pepsin 0*23 grm. 



