698 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



put. One of these plates is shown in place with three others in front, 

 the hollow one for hard and other substances which require fixing in 

 some kind of cement, &c., and the oblong one for preparations of larger 

 size. The vessel is closed by a top with a glass surface, having a 

 central hole through which the circular plates project slightly. The 

 knife — the edge of which only comes into contact with the substance 

 cut — is fixed into a triangular frame, which moves freely on the glass 

 surface. By the three screws at the angles the frame, and with it the 

 knife, can be raised or lowered for adjustment in any desired plane. 

 The other two screws attached to the frame are for supporting the 

 knife, which has two notches fitting into grooves near the points of the 

 screws. A third horizontal screw presses the knife against the first 

 two screws and keeps it tightly in place. I'he screw seen at the left- 



FiG. 164. 



hand side of the ice vessel is for the purpose of clamping the top, and 

 the indiarubber tube carries away the drainings as the ice melts. It 

 is claimed that this instrument will keep the preparation in a frozen 

 state for hours after once charging with ice and salt, and readily cuts 

 sections y^Vir i'^^^ thick. 



The method of using the microtome is as follows : — 

 Eemove the cover and fill the chamber with equal parts of pul- 

 verized ice and salt, care being taken not to allow the mixture to touch 

 the under side of the cover, which, when replaced, must be firmly 

 secured by the clamp screw for that purpose. The substance to be cut 

 must be placed on the surface of one of the circular plates, and sur- 

 rounded with a little common gum-water, which readily congeals and 

 tlnis holds the specimen firmly in position, which will solidify shortly 



