74f W. BEVAN LEWIS. 



factorily the processes of the cells of Purkinje, or the finest of 

 twigs which arise from the pyramidal layers of the cerehral 

 cortex. No reagent has found such claims upon our atten- 

 tion for this purpose as chloral hydrate. For some time 

 past I have employed this reagent for the demonstration of 

 nervous elements, having been directed to its use by a paper 

 by Victor Butzke.^ This writer states : — " Eine solution 

 von chloralhydrat in wasser, von 1 : 1 bis 1 : 10 pro cent, 

 auf das frische Gehern angewandt, lost zwar das Hirnfett 

 nur theilweise, versetzt es aber in einen Zustand, in welchem 

 es molecular zerfallt, so das es leicht aus dem Zusammen 

 hange mit den Formelementen herausgewaschen werden 

 kann. Als ganz vorziiglich babe ich eine combination 

 von Hyperosmiumsaure (| per cent.) mit chloralhydrat 

 gefunden, was nach einander angewandt, in der Schonheit 

 der Isolation der Hirnelemente bald, so glaube, ich die alten 

 Rivalen weit hinter sich lassen wird." The latter statement 

 1 have not been able at present to confirm; but as to the 

 full value of chloral hydrate for such purposes I can fully 

 confirm the opinion of Butzke. Still another important 

 quality belongs to this compound, namely, that it is a power- 

 ful solvent of aniline black, so that we possess in it the very 

 valuable combination of qualities most likely to give us the 

 best results. This assumption, put practically to the test, has 

 answered my highest expectations. The process I employ 

 I can confidently recommend, especially for the demon- 

 stration of the cerebellar cortex. The sections are first 

 deeply stained in aniline dye, gently washed from superfluous 

 colour in distilled water, and removed to a porcelain vessel 

 containing the solution of chloral, where they are allowed to 

 remain from twenty to thirty minutes. They are next trans- 

 ferred to the following solution : — Of solution of chloral 

 hydrate and oil of cloves equal parts. Alcohol enough to 

 dissolve perfectly and form a perfectly clear solution. The 

 alcohol must be added by degrees, the mixture being stirred 

 with a glass rod, and care being taken to avoid any excess. 

 During use this mixture must of course be kept carefully 

 covered up to avoid evaporation. It will now be found that 

 the sections are clearing up, whilst all diff"use staining is still 

 further removed by the chloral. We should remove one 

 occasionally to a slide, and examine under a low power the 

 progress made, and when satisfactory results are obtained, 

 the sections should be washed with a little alcohol, floated 

 up by one or two drops of clove oil, and when perfectly clear 

 mounted in balsam. In regard to the essential oil used I 

 ' 'Aichiv fur Pyschiatiie uud Nervenkranklieiten,' 1872. 



