1894.] MICROSCOPICAL JOURNAL. 63 



as the section just drawn. The edges are trimmed to tit tlie 

 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 invented 

 l)y Dr. Paul Mayer. He uses carminic acid instead of commer- 

 cial carmine. In Leipzig carminic acid costs only eight cents 

 }ter gramme. 



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

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

 osmicacid. Alum carmine will not do this. It tinges the pro- 

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

 objects mounted entire is not recommended because it ma}' 

 overstain 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 ofl' 

 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 liuid by 

 replacing the 1 percent chromic acid with 1 per cent platinum 

 chloride. It is made as follows : 



Platinum chloride, 1 per cent IT) parts. 



Osmic acid, 2 per cent 4 parts. 



Glacial acetic 1 part. 



For example, take one of the sealed glass tubes containing a 

 granune of osmic, as it is commohh' sold, and break it in a bot- 

 tle of 300cc.. capacity ; pour on it 50cc. of pure distilled water^ 

 r2*cc.. glacial acetic, and 187l'CC. of 1 per cent solution of 

 jdatinic chloride. Shake and put aside over night. \\'hen the 

 osmic has dissolved the mixture is ready for use. 



DIATOMS. 



The Grandest Collection on Earth. — The British Museum 

 has purchased the great collection of 30,0UU slides of diatoms 



