62 THE AMERICAN MONTHLY [Feb., 



entiate. Professor Haag, in the laboratory of Toledo Medical 

 College, demonstrates this layer beautifully by the use of sul- 

 pho-indigitate of sodium in the following manner : 



The skin is hardened in alcohol in the usual manner, cut and 

 stained preferably in Woodward's Carmine for the reason that 

 sections can be transferred directly from alcohol to the staining 

 fluid without first being hydrated. After being stained, bleached 

 and washed in alcohol until all trace of the acid used in the 

 bleaching fluid is removed they are placed in alcohol, to which 

 a sufficient quantity of a saturated aqueous solution of sulpho- 

 indigitate of sodium is added to give it a sky blue color, in 

 which ttiey are left until the bluecoL)r is taken up. If the al- 

 cohol has not been tinged too blue, no hurry need be exer- 

 cised, as the sections are dehydrating at the same time they are 

 staining. 



They are then cleaned in oil of cloves and mounted in bal- 

 sam, in the usual way. Upon examination., f^tratum lucidum 

 will be seen of a bei.utiiul blue color and clearly defined, while 

 the heavy epitheliid cells of the covneum will also be distinctly 

 mapped out. 



A little caution is necessary, for if too much of the sulpho- 

 indigitate of sodium solution be added to the alcohol, other 

 portions of the tissue will give up the carmine and take up 

 the blue stain. The stratum lucidum, having the greater 

 affinity foi the soda, will take it first and quickly, and if more 

 of it be present than will satisfy its wants, other parts of the 

 tissue will take it up and somewhat mar the differentiation and 



spoil the beautiful appearance of the specimen. American 



Medical Compend. 



Constructing an Aquarium for Use with High Powers.- 



M. Schandiun has just published in the Zeitschrift fur wissens - 

 chaftliche Mikroskopie an interesting article entitled : Ein Mi- 

 kroaquarium welches auch zur Paraffin Einbettung fur Kleine 

 Objecte benutzt warden Kann. 



What is especially to be remembered in that communication 

 is the method used by the author in constructing an aquarium 

 which can be used to examine microscopical objects under a tol- 

 erably high power. 



A rectangle or a square is cut in a slide (near one of the edg- 

 es.) Then upon the two faces a lamel of glass larger than the 



