Production of Sections 281 



The advantage of staining solely in alcoholic solutions is 

 that the sections have not to be passed from strong alcohol 

 into water, water acting injuriously upon some tissues, but 

 not affecting the majority of subjects in the least if care be 

 taken to make the transfer from strong alcohol to water 

 as gradual as possible by the intervention of gradually 

 decreasing grades of alcohol. Passing from water to strong 

 alcohol should be through gradually increasing grades 

 of alcohol; hence the use of various grades of alcohol 

 recommended to be in readiness in the grooved porcelain 

 troughs and elsewhere. The various grades of alcohol are 

 prepared sufficiently correct enough for practical work as 

 follows : 



For 30 per cent, alcohol take 90 per cent, alcohol, 

 300 c.c. ; add distilled water, 620 c.c. 



For 50 per cent, alcohol take 90 per cent, alcohol, 

 600 c.c. ; add distilled water, 420 c.c. 



For 70 per cent, alcohol take 90 per cent, alcohol, 

 800 c.c. ; add distilled water, 200 c.c. 



For 90 per cent, alcohol methylated spirit as purchased 

 (see p. 264). 



Eectified spirit of the British Pharmacopoeia is 84 per 

 cent, alcohol; 98 per cent, alcohol is the usual absolute 

 alcohol. 



The formulae above given are convenient quantities for 

 half Winchester bottles. 



We do not propose to give the endless number of formulae 

 for mixing stains ; such in abundance, together with direc- 

 tions, will be found in the three following works : * Botanical 

 Microtechnique,' by Dr. A. Zimmermann ; ' The Micro- 

 tomist's Vade-Mecum,' by Mr. A. Bolles Lee both pre- 

 viously mentioned ; ' Methods and Formulae,' by Mr. P. W. 

 Squire, an invaluable little work. 



We must point out that the most simple formula will 

 often prove the best friend to the student. A certain 

 amount of quackery exists among microscopists, as in other 

 persons, and there are to be found men willing nay, 



