1899] MICROSCOPICAL JOURNAL. 163 



the macroscopical and microscopical characters of this or- 

 g-an, prepared slides and made drawings. He examined a 

 large number of these g-lands. In all these was either a 

 definite central cavity (a ventricle) or else a collection of 

 specialized tissue resembling neuroglia. Abnormal con- 

 ditions appeared in the pineal glands of insane patients. 



Varnishes and Labels. — Many things will do : — Sealing 

 wax dissolved in methylated spirit, copal varnish, gold 

 size, printers' varnish mixed with any pigment of the de- 

 sired color. Pigments can also be ground up in French 

 polish, and used for the purpose. 



MICROSCOPICAL MANIPULATION. 



Fixing and Staining Blood. — Absolute alcohol is the most 

 reliable fixative known. Eosin and Methylene blue are 

 the standard stains for demonstrating all the ordinary 

 characteristics of normal and abnormal blood. But eosin 

 under certain circumstances cannot be made to stain cer- 

 tain cell granules. This has led to combination stains such 

 as the Ehrlich-Biondi and Ehrlich's later triacid, but thev 

 are troublesome to use and require special fixing- methods. 

 If to alcoholic eosin solution or alcohol soluble eosin is added 

 methylene blue, brilliant grass-green crystals are precipi- 

 tated. When methylene blue is added to a watery solution 

 of eosin or to water-soluble eosin amorphous and darkme- 

 talic-green crystals result. Consequently preparations 

 have been put on sale consisting of eosin methylene blue 

 mixtures designed to avoid these precipitates. The first 

 named crystals are very sparingly soluble in cold alcohol 

 but more so in hot alcohol from which they can be re- 

 crystalized. This shows them to be a deffinite compound 

 body. Boththese kindsof crystals melt at 227degs. C. taken 

 on the suifaceof mercury. Because of their being- so 

 poorly soluble in alcohol these crystals are not useful as a 

 blood stain without previous fixation of the film. Dissolved 

 in chloroform or aniline oil, they give dark violet colored 

 solutions. Watery solution gives amorphous precipitates 

 of the two dyes which is very sparingly soluble in water, 



