244 THE MICROSCOPE 



fixed level. Stirling's instrument is one of the earliest, a descrip- 

 tion of which is found in Stirling's " Histology." Dr. Ray's, an 

 account of which will be found in Foster's Journal of Physiology, 

 Vol. II., p. 19. It is made by the Cambridge Scientific Instru- 

 ment Company, as is Caldwell's ribbon section microtome. This 

 latter is an excellent instrument, especially for class working. Its 

 drawback is the expense, but lately a cheaper form has been made. 

 Dr. Urban Pritchard's {Lancet, Dec. nth, 1875) ^"^ Williams' 

 freezing microtomes. — The latter is most often in general use. It 

 is known as Swift's " Tub," and has recently been adapted for use 

 with ether as a freezing agent by Dr. Groves.* For those who do 

 not mind the inhalation of atmospheric air charged with ether, 

 the best and simplest ether-freezers for use \\\\.\\ Swift's knife is 

 Fearnley's microtome. This is simply the top of the Grove- 

 Williams's instrument, supported by three legs. The ether nozzle 

 is immediately under the frame of the glass plate, and the bottle 

 of ether stands beside the machine on the table. This is also 

 made by Messrs. Swift and Son (Cole). Dr. Bevan Lewis's ether- 

 freezer is specially valuable for rapid freezing. 



The latest microtome is Cathcart's ether-freezer, and I can 

 strongly recommend it, from personal experience, for cheapness, 

 simplicity, and efificacy. It cannot be approached by any ether 

 or ice microtome I know. The total cost of microtome with plane- 

 iron is only about 17s. 6d. The maker is Frazer, of Lowthian .St., 

 Edinburgh, but it can be obtained from nearly all opticians. With 

 the expenditure of two drams of ether, 60 or 70 sections can be 

 cut in almost as many seconds. In using the microtome a little 

 care is needed, as several have told me the tissue would ;/(?/ remain 

 on the plate when frozen. The secret of this is that a little gum 

 solution should h^ first placed on the plate and almost frozen. The 

 tissue to be cut is placed upon it and surrounded with gum, and 

 the whole frozen. The tissue is elevated to the knife by a revolu- 

 tion of the screw with the left hand, whilst the right drives the 

 plane-iron, which must be held with the edge far below the level 

 of the rest of the iron, and the screw-movement and the push of 

 the iron must take place alternately. When a mass of sections 



'' Jounml of Quek. Micros. Club, Oct., 1S81, Vol. VI., p. 293. 



