ETHER FREEZINO .MICROTOMES 473 



surface to be made with precision, sections 1 in. x f in. having 

 been cut by it without difficulty. 



It consists of a solid cast-iron base, A, 10 in. x 4J in., which 

 rests upon a mahogany block. Extending the whole length of the 

 upper surface of the base is a V-shaped gutter, on the planed sides 

 of which slides a heavy metal block, B, on the flat top of which 

 the razor is secured (any ordinary razor can be used), the tang 

 being grasped between two flat pieces of iron, which are press* M! 

 together by a winged nut, C. The razor by this arrangement can 

 be secured at any desired angle to the direction of its motion to 

 and fro. 



The freezing-chamber is formed by a short vulcanite cylinder, ] ), 

 its lower end being screwed into a' "brass base, E. To its upper end 

 is fastened by two bayonet-catches a brass plate, F, on which the 

 tissue to be cut is placed. Inside the cylinder, I), and rising from 

 the base, E, is an ordinary spray, the air and ether being supplied 

 through tubes, g and H, passing outside through the base. There 



FIG. 400. Dr. Hayes's ether freezing microtome. 



is also an opening in the floor of the chamber communicating with 

 the tube, to allow the overflow of ether in case of any accumulation 

 inside the cylinder ; any such overflow may be returned by the tube 

 to the ether supply bottle, K. The freezing- chamber is secured to 

 the top of the micrometer-screw arrangement. Z, which is of the 

 simplest form, but has a perfectly smooth and regular motion. The 

 nut is divided to indicate a section O01 mm. in thickness, but half 

 this thickness can be cut without difficulty. 



The method of using the microtome is very simple. The slide 

 and block, D, having been carefully rubbed clean and well oiled, the 

 razor is clamped at any desired angle, the bottle, K, is filled with 

 ether (good dry methylated ether answers perfectly), and the piece 

 of tissue to be cut, having been previously saturated with thick gum 

 solution, is placed upon the plate F, and the spray which plays upon 

 the under surface of the plate, F, set working by the hand-pump, 

 M ; in a short time the tissue will be frozen quite through, and if a 

 number of sections are required, an occasional stroke or two of the 



