1899] MICROSCOPICAL JOURNAL. 29 



snug- fit around the tube of the instrument. At the back 

 part of the camera must be attached a frame grooved to 

 admit sliding in the plate-holder easily. A similar plate- 

 holder may be used to receive the pane of ground glass. 

 Use sunlight, kerosene, gas or incandescent electric light 

 at pleasure. 



Jones' Excelsior. — W. Jones and Co., 5 Devonshire St., 

 Holborn, W. C, London, offer for 67 cents post paid a 

 microscope with nickel plated tube and extra finished solid 

 brass stand, adjustable reflector and object glass magnify- 

 ing 3,000 "volumes" — whatever that may mean. Probably 

 it may magnify 10 diameters. That is very good for 67 

 cents. Not being worth one dollar, probably it can get 

 within the U. S. Chinese wall free of duty and will make a 

 nice present for children. International postal order for 

 2 shillings 9 pence can be got at all money order offices. 



MICROSCOPICAL MANIPULATION. 



Frozen Sections. — To prepare the tissue, fix and harden 

 it in a mixture of one part formol to ten parts Muller's 

 fluid, during three hours. Wash and put in dilute alcohol, 

 afterward up to 95 per cent alcohol. Remove to solution 

 of acacia and sugar. Then freeze, or place in 4 per cent 

 formaldehyde for 15 minutes and then freeze. When pre- 

 pared in some such manner or even if perfectly fresh, put 

 the tissue with some formol and gum acacia fluid upon the 

 specimen holder of the microtome. Then play down upon 

 it a small stream of ethyl chloride, methyl chloride or an- 

 estile (a mixture of the two). Hold the tube of ethyl 

 chloride about a foot above the specimen, move it from 

 point to point in the specimen until the upper portion is 

 coated with crystals of ice which are very minute and do 

 no harm. The specimen is frozen in 40 to 60 seconds. Af- 

 ter cutting, place the sections in 50 per cent alcohol and 

 mount as usual. Stain when desired. Fifteen minutes will 

 suffice for the entire operation. 



Urinary Sediment. — These may be photogi'aphed with 

 an exposure of 40 to 60 seconds according to rapidity of 



