38 GENERAL BIOLOGY. 



4. Crush the cells stained with magenta by press- 

 ing forcibly on the cover-glass with the 

 handle of scalpel or needle-holder. What 

 details of structure (see above, II. 1 and 2) 

 are visible after crushing ? Does the ma- 

 genta affect all parts of the cell equally ? 

 Y. Physiology. 



1. Put a large drop of yeast into each of three 



test-tubes (previously labelled) containing 



(a) Distilled water ; 



(b) Pasteur's fluid without sugar ; 



(c) Pasteur's fluid with sugar. 



Stop the tubes with cotton and keep side by 

 side. Examine the tubes from day to day 

 with the naked eye. Record the result and 

 explain. 



2. Put a drop of yeast into each of two test-tubes 



of the same size (previously labelled) con- 

 taining equal amounts of Pasteur's fluid 

 with sugar. Stop both well with cotton. 

 Boil one for five minutes. Keep them side 

 by side. Examine the tubes with the naked 

 eye from day to day. Record the result 

 and the explanation. 



