and Laboratory Methods. 



1163 



have seen a shoe knife successfully used ; but in this case the back was strength- 

 ened by soldering a knitting needle on one side and a rod cut from a stove poker 

 on the other. Assuming, then, that a knife is at hand, the next requisite is the 

 holder, which consists of a piece of wood about four by seven inches, having a 

 U-shaped cut-out at the top, two inches wide and three inches deep. This leaves 

 two prongs each an inch wide into which small wire nails are driven so that the 

 razor (R) may rest upon them when it is in position. Spring clips of some sort hold 

 the razor firmly in place. For the clips, stout wire an eighth of an inch thick is 

 good. Each wire may be fastened to the board by double-pointed tacks. Near 

 the bottom of the board and in the center is the screw (S). A common screw will 

 answer, but a fine threaded screw passing through a nut is better. In either case, 

 however, a large disc may be soldered to the screw head for increased delicacy 

 in operation. The "holder" complete is now, by means of a pair of hooks and 

 eyes, to be made attachable to the end of a box so that turning the screw 



Fig. I. 



Fig. 2. 



gives a delicate movement to the razor. The screw point should work against a 

 small metal plate on the box. Tension is secured with a rubber band or spiral 

 spring. (Reference to the diagram will make the idea clear.) The " holder " 

 should be so placed that the razor edge will be two or more inches higher than 

 the top of the box. Now, when an adjustable object-holder is provided, the 

 microtome is completed. To make the object-holder, a board somewhat shorter 

 than the box, a block, and a straight-grained stick about one-half an inch in 

 cross section are necessary. Fasten the block near one end of the board, nail 

 the stick to the block (as indicated in the diagram), and the microtome is ready 

 for service. 



In use, the paraffin block (O) is fastened to the end of the stick with melted 

 paraffin, and proper adjustments are made with reference to the razor. Then, 

 downward pressure on the stick cuts the section, while clockwise movement of 

 the screw regulates the thickness. Serial sections are readily made, if the 



