1894.] MICROSCOPICAL JOURNAL. 63 



as the section just drawn. The edges are trimmed to fit the 

 paper outline and the successive layers of wax are put together 

 in the same order that the sections occupied before being; cut. 



MICROSCOPICAL MANIPULATION. 



Mayer's Carm-alum. — This is a new carmine stain invente<l 

 by Dr. Paul Mayer. He uses carminic acid instead of commer- 

 cial carmine. In Leij^zig carminic acid costs only eight cents 

 per gramme. 



Carm-alum is a dark-red liquid with intense staining power. 

 It gives a beautiful stain to objects that have been fixed in pure 

 osmicacid. Alum carmine will not do this. It tinges the })ro- 

 toplasm slightly as well as the nucleus. Its use in the case of 

 objects mounted entire is not recommended because it may 

 overstaiii and render them opaque. 



Mix together in a suitable vessel one gramme of carmine acid , 

 ten grammes of ammonia alum, 200cc. distilled water. Heat to 

 a boiling point, dissolving the ingredients, after cooling pour ofi' 

 or filter the liquid. It is now ready for use. A small crystal 

 of thymol or of some other antiseptic may be added to keep it 

 free from organisms. 



The application of this stain to protozoa, etc., has been des- 

 cribed in Natural Science for August, 1893, p. 114. 



Hermann's Fluid. — This differs from Flemming's fluid by 

 replacing the 1 percent chromic acid with 1 jx'r cent platinum 

 chloride. It is made as follows : 



Platinum chloride, 1 per cent 1.") parts. 



Osmic acid, 2 per cent I parts. 



Glacial acetic 1 part. 



For example, take one of the sealed gla.«s tubes (;ontaining a 

 gramme of osmic, as it is commonly sold, and break it in a l)()t. 

 tie of 300cc. capacity ; ]>our on it oOcc. ot jjure distilled water 

 12ilcc. glacial acetic, and bSTicc. of 1 ])er cent solution of 

 phitinic chloride. Shake and put aside over night. When the 

 osmic has dissolved the mixture is read}' for use. 



DIATOMS. 



The Grandest Collection on Earth. — The iJritisii Museum 

 has purchased the great collection of 30,000 slides of diatoms 



