392 APPENDIX 



40. Sodium Hydrate. 



Use, — With copper sulphate it forms a test for glucose. 



Preparation. — Dissolve the sticks of sodium hydrate in 

 three or four times their weight of distilled water. Keep 

 in a bottle with a glass stopper, the latter having been 

 smeared with vaseline to prevent sticking. 



41. Sugar. 



Use. — Concentrated solutions plasmolyze living cells ; used 

 also as a culture medium for yeast; and to cause the 

 germination of pollen-grains. 



Preparation. — To make the twenty per cent, solution dis- 

 solve twenty grams of granulated sugar in eighty cubic 

 centimetres of distilled water. From this the ten per cent, 

 and two per cent, solutions may be made by dilution. 



42. Sulphuric Acid. 



Use. — The concentrated acid dissolves cellulose cell-walls 

 and swells starch grains ; turns blue those cellulose cell- 

 walls which have previously been saturated with a solu- 

 tion of iodine. For the last reaction dilute solutions are 

 preferable. 



Preparation. — Dilute the concentrated colorless acid to the 

 strength desired. Make the dilute by mixing equal parts 

 of the concentrated solution and distilled water ; the sev- 

 enty-five per cent, solution by mixing seventy-five parts 

 of the acid with twenty -five parts of distilled water. 

 Keep in bottles with glass stoppers. 



43. Warm Stage. 



A simple warm stage consists of a T-shaped piece of 

 sheet copper six inches long by three inches wide. In 

 the middle of the cross-piece is punched a hole whose 

 diameter is slightly greater than that of a cover-glass. 

 When used the warm stage is placed on the stage of the 

 microscope with the tongue projecting forward, and the 

 hole over the opening in the stage. On the cross-piece 

 is laid the slide, the whole being held securely in place 



