APPENDIX A 



THE following list of reagents is not intended to be an 

 exhaustive catalogue of the various substances in use in the 

 Botanical Laboratory : it includes, however, those reagents which 

 are considered to be of the greatest importance, together with 

 notes on their proper preparation, and uses. 



Acetate of Potash. A strong solution in water is used as 

 a mounting medium for preparations of green parts of plants : 

 in this solution they retain their green colour for a long time. 

 Aluminium acetate may also be used for the same purpose (p. 53). 



Acetic Acid. This is usually used as a dilute solution in water 

 (1 per cent.) : it dissolves calcium carbonate with evolution of 

 bubbles of C0 2 (see p. 140) : it brings out the nuclei very clearly, 

 and with this object in view it is used with methyl-green : it may 

 also be employed as a corrective after treatment of a preparation 

 with potash, if the tissues have become too transparent. Glacial 

 acetic acid is also sometimes used in the preparation of the apex 

 of Fucus. 



Alcohol is of universal use as a solvent, precipitant, and harden- 

 ing agent. Absolute alcohol is the best, but for most ordinary 

 work strong methylated spirit will do (see p. 5, &c.). It dissolves 

 chlorophyll and other colouring-matters (pp. 47, 128), resins 

 (p. 65), ethereal oils, and some fixed oils (p. 223) : wax is soluble 

 in hot alcohol. It precipitates some substances, such as sugars 

 (p. 222), inulin (p. 119), and asparagin (p. 228). It coagulates 

 proteids, and has a peculiar action on some crystalloids. It acts 

 as a hardening agent on cell- walls, sometimes rendering them too 

 brittle : this may be overcome by soaking the material, before 



