15 



59. Microtome devised by Professor Rutherford for 

 cutting frozen tissues. Exhibited by J. Gardner. 1876. 



As in No. 57, there is a piston which can be raised in n 

 well by means of a micrometer screw. The tissue, soaked 

 in gum, is placed in the well, and a freezing mixture placed in a 

 trough around this. The razor slides upon a plane surface of 

 brass, and there is a screw clamp by which the apparatus can be 

 attached to a table. For description, .see Rutherford, " Outlines 

 of Practical Histology," London, 1875. 



60. Microtome designed by Professor C. S. Roy for 

 cutting objects frozen by the ether spray. 



Made 1\j the Cambridge Scientific Instrument Co. 

 E. 30. 1887. 



The object, preferably soaked in gum, is placed on a thin 

 metal plate, upon the under surface of which the spray is directed. 

 The razor is carried by an arm which rotates about a vertical 

 axis, and is made to descend a little between every cut l>y means 

 of a ratchet. An additional clamp is supplied for holding objects 

 which have been embedded. 



61. Microtome for cutting objects embedded in 

 paraffin into ribbons, known as the " Rocking Micro- 

 tome." 



Made bi/ the Cambridge Scientific Instrument Co. 

 E. 144. 1888. 



The razor is held horizontally with its edge upwards by two 

 clamps, and the object is fixed to the end of a lever which 

 moves up and down close to it. The axis of the lever rests upon 

 the upright arm of another lever, which has a horizontal arm 

 actuated by a micrometer screw, so that as it is raised the object 

 is thrown forward against the razor. The lever which carries 

 the object is moved up and down by a handle placed on the 

 same axis as the micrometer screw, and actuating it by means 

 of a pawl and ratchet ; a movable piece, which lifts the pawl 

 from the ratchet for any desired interval, provides the means of 

 varying the thickness of the section. 



62. Microtome, similar to No. 61. 



Exhibited by the Cambridge Scientific Instrument Go. 



1885. 



63. Microtome for cutting embedded sections, con- 

 sisting of a circular plate of glass supported by two 

 pillars upon a heavy stand. In the centre is a well 

 with a piston moved up and down by a micrometer 



B 2 



