THE AUTHOR S LABORATORY MICROTOME. 



15 



tissue be too soft to withstand such treatment, it is best cemented to 

 a cork, and the cork then fastened in the clamp. A screw-thread is 

 cut upon a short cylinder, which works in a corresponding thread 

 chased on the inside of the well-tube. The short cylinder carries the 

 knife-plate, and, as the latter is turned to the right, the whole de- 

 scends and the tissue projects, ready to be sliced off. 



THE AUTHOR'S LABORATORY MICROTOME. 



For certain work, some form of microtome becomes necessary in 

 which the operator is relieved from supporting the knife. Fig. 8 is a 

 sketch from such an instrument which I have contrived and which 

 has been in daily use in my laboratory for over three years. 



The carriage A, supporting the knife B, is of solid cast-iron ; and 

 has, upon the under side, a V guide, which fits into the longitudinal 

 groove of the base D. Parallel with this groove is a smooth flat 





FIG. 8. THE AUTHOR'S LABORATORY MICROTOME. 



The instrument consists of a very heavy cast-iron bed upon which a carriage supporting a 

 knife is made to slide. The tissue is cemented with paraffin (or held in an adjustable clamp 

 not shown in the cut) to a table, which can be raised by a fine steel screw. The thickness of the 

 section to be cut is controlled by turning the milled head actuating the finely threaded screw. 



surface, upon which also travels the rib E of the knife-carriage. A 

 second Y has been avoided, in order to diminish friction. The knife 

 is clamped rigidly to the upper surface of the carriage, by means of a 

 Willis' tool-holder, consisting of a steel plate F, a nut G-, and washer 

 H. 



The mechanism for supporting and positioning the tissue not shown 

 in the sketch is built upon a plate I, which can be quickly fixed to 

 the body of the microtome at the height and lateral incline required 

 by the large set-screws J, J'. The mechanism for raising the tissue 

 to the knife, between the cuts, consists of a screw K, of fifty threads 

 to the inch which, working in the nut L, elevates the bevelled slide 



