124 THE AMERICAN MONTHLY [Apr., 



with all the strength possible, giving a slight lateral movement 

 at the same time. If then held up to the light, the meat will 

 be found almost transparent with a slight opalesence. If now 

 placed in the compressor frame, and screwed down, the pre- 

 paration will be ready for microscopical examination. In about 

 24 hours or more, the water in the specimen will evaporate, and 

 if the glasses be removed from the compressor and separated, 

 the preparation will be found to be a very thin film, transpar- 

 ent and dry, which can be removed and cut in suitable pieces, 

 and mounted in the usual way, in its natural condition or 

 stained. The compressors mentioned are those used by the 

 meat inspectors of the U. S. Bureau of Animal Industry and 

 made by Bausch & Lomb. They are illustrated at No. 1662 of 

 their last catalogue. 



The glasses are 3x2 inches, and about 1- 10 of an inch thick, 

 and will bear a considerable pressures without breaking. They 

 offer great facilities to microscopists, as there are a large num- 

 ber of objects that require pressure during preparation, especially 

 in Botany and Insect life, and from the size, quite large objects 

 can be introduced. It is cheap costing only two dollars includ- 

 ing the two glasses. John Michels. 



The Pelham, Boston, Mass. 



MICROSCOPICAL MANIPULATION. 



Microphotographs by Lamp-light. — Dr. Borden, IJ. S. A., 

 of Fort Adams, Newport, has taken some fine microphotos of 

 bacteria with lamp-light. He uses a Laverene three inch magic 

 lantern with four inch condensors. The lantern objective is re- 

 moved and the middle wick only lighted. The substage con- 

 denser is focussed accurately on the front surface of the stereop- 

 ticon condensor. This gives light with a } inch oil immersion 

 so that a magnification of 1000 diameters can be focussed on the 

 screen. With a 1-5 inch objective he uses a one inch objective 

 on the substage. He uses a Cramer's Isthochromatic rapid 

 plate and develops with hydrochromion. This plate is spec- 

 ially prepared for lamp work and gives the best results of many 

 different makes. AH to 2 minutes exposure is needed for 

 1000 din meters. 



