374 KANSAS UNIVERSITY SCIENCE BULLETIN. 



consists of a holder for an ordinary safety-razor blade and is 

 made as follows : Two pieces of steel are used as supports ; 

 they are in shape, in cross-section, plain w^edges, as shown in 

 the accompanying illustration. The inner faces are planed 

 to fit each other accurately, no allowance being made for the 

 thickness of the razor-blade. To secure sufficient rigidity the 

 supports should be as thick as the carrier of the microtome on 

 which the knife is to be used will permit. The two parts of 

 the support are held together by two screws, as illustrated, 

 the screw-heads being countersunk so as to have bearing- 

 surfaces parallel with the inner surfaces of the supports. The 

 dimensions of the knife described are : 



A— B, 126 mm. 



B— D, 22 mm. 



D— C, E— D, 5 mm. F— G, 18 mm. 



i 



v-^e 



The apparatus has been found in practice to work quite satis- 

 factorily for the softer tissues, but ^ not sufficiently rigid for 

 the denser ones, such as skin. 



