APPENDIX A 263 





occasionally wetting the cardboard on the slide with freshly 

 boiled, distilled water. 



The liquid to be used will of course vary with the nature of 

 the object to be observed. In the case of Algae, water may be 

 used ; in the case of Fungi, decoctions of various organic sub 1 - 

 stances (fruits, animal tissues, &c.), or a solution of sugar, 

 according to the habit of the Fungus. For observing the ger- 

 mination of the spores of Mosses and Ferns, water will suffice ; 

 but in the case of pollen-grains a solution of sugar is necessary 

 (i 20 or even 30 per cent., the concentration being different for 

 different plants) ; for observing the process of cell-division in 

 the hairs on the stamens of Tradescantia, a 2 per cent, sugar- 

 solution may be used. 



