and Laboratory Methods. 



as above, but the staining is slower, taking 10 to 15 minutes instead of 3 to 4. 

 For thick sections 4 volumes of water only should be added to 1 volume of 

 picro-carmine, and the sections may be boiled in the mixture for 2 to 3 minutes. 

 The stain is stated to be chiefly that of carmine, but picric acid can be added 

 to the alcohol through which the sections are passed after leaving the carmine. 

 The method has been especially used on the central nervous system, and after 

 the following hardening agents : Miiller's fluid, potassium bichromate, Weigert's 

 chrome-alum mixture and formalin. Sections hardened in chrome-alum, in which 

 the meduUated nerve fibres have been stained (Heller-Robertson method), can 

 also be stained with carmine by the methods given above. r. p. 



: 



] 



NEWS AND NOTES. 



The following interesting information concerning a special feature of the 

 government exhibit at St. Louis has been received from B, J. Howard, of the 

 Bureau of Chemistry, United States Department of Agriculture: 



" I am sending a print showing a new devise 

 which we have invented in the form of an exhi- ^^ 

 bition microscope to be used in connection with 

 our exhibit at the St. Louis Exposition this sum- 

 mer. It consists of substituting a specially de- 

 vised stage for the one furnished on the Bausch 

 & Lomb stand. Style A. The new stage carries 

 three cog-wheels so arranged that for each half 

 revolution of the small pinion the large one is 

 driven forward J,y revolution. The large wheel 

 carries a circular plate-glass disk of 5 inches 

 diameter attached to it by means of a thumb- 

 screw passing through a hole in the center of the 

 disk. The specimens are carefully mounted so 

 that their centers are all an equal distance from 

 the center of the disk, and covered with ^^-inch 

 cover-glasses. In this way each disk will carry 

 20 specimens. 



" On the shaft carrying the hard rubber button 

 by which the small pinion is turned, is an inter- 

 mittent gear arrangement (only part of which is 

 seen in the print)^ which drives a dial with 

 figures or names upon it, indicating each of the 

 specimens as it comes into view under the objective. 



" The whole instrument, with the exception of the ocular and hard rubber 

 button, is enclosed in a glass case, the focusing being accomplished by means 

 of raising or lowering the ocular — a set-screw preventing its being totally re- 

 moved from the draw-tube." 



