APPENDIX A 513 



short time, and be then washed with water, it will be found that 

 the cell-walls have become swollen and transparent, that the 

 protoplasm has become deeply stained, and that the sieve -plates 

 are very well brought out. Lignified tissues treated with this 

 fluid assume a yellow colour, as they do when treated with aniline 

 sulphate. 



Moist Chamber (see Water). 



Nitric Acid colours cuticularized cell-walls and proteids 

 yellow ; it also causes swelling up of cellulose and of lignified 

 cell- walls. When diluted with water it is useful for dissolving 

 the crystals of calcium oxalate which are frequently present in 

 the cells (pp. 109, 178). It is used with ammonia as a test 

 for proteids (xanthoproteic reaction) ; with potassium chlor- 

 ate as a test for suberin, and as Schulze's macerating fluid 

 (p. 104). 



Olive Oil is used as a medium for mounting aleurone-grains, 

 so as to see them unaltered (p. 223). 



Orcin. A solution in alcohol is used as a test for inulin. 

 Sections are to be soaked in the solution and subsequently 

 warmed with strong hydrochloric acid : an orange-red colour 

 shows the presence of inulin. 



Osmic Acid is used in O'l-l'O per cent, solution in water, for 

 fixing and hardening protoplasm (p. 5) : it also stains fats black 

 (p. 223). The solution should be kept in a well-stoppered bottle 

 in the dark. 



Paraffin is used as an embedding medium for small or delicate 

 objects (p. 10). Paraffins of varying hardness and temperature of 

 melting-point may be obtained : the best for ordinary use is a 

 mixture which shall melt at a temperature of 50 to 60 C. 



Phenol (Carbolic Acid). Used, together with hydrochloric 

 acid, as a test for lignin. The best preparation of it is its solu- 

 tion in hydrochloric acid : this is prepared by dissolving carbolic 

 acid in warm hydrochloric acid, adding, whilst the mixture 

 is cooling, sufficient hydrochloric acid to dissolve any precipitate 

 that may be formed. Lignified cells, treated with this mixture 

 and exposed to sunlight, assume a bright green colour in 

 consequence of the presence of coniferin. It may also be used, 

 instead of creosote, together with turpentine, as a clearing 



L L 



