2228 Journal of Applied Microscopy 



The knife is moved in the same manner as in the Leyser microtome just described. 

 The following description refers to one of the earlier instruments of this 

 type. Schanze is an instrument maker in Leipzig, and copied in part the 

 system of construction used by Leyser, for he employed a horizontal way along 

 which the carriage moves, which carries the knife. The large head of the micro- 

 meter screw was graduated and an index was placed so that one could easily 

 turn the head of the screw any desired distance and obtain the desired raising of 

 the object and thickness of section. But a still more important improvement, 

 which appears in the Schanze instrument, is the introduction of the adjustable 

 object holder, so devised that it can be turned around two horizontal axes and, 

 after turning, be clamped securely in any position. By this device the plane of 

 the section can be adjusted and any desired angle secured. In addition the 

 actual object holder was fastened upon a vertical rod which fitted into a vertical 

 hole so that the object holder could be revolved around the vertical axis. After 

 the desired position is obtained, the rod can be fastened by means of a clamping 

 screw. We have in this object holder all of the adjustments which are to be 

 found in the best modern patterns, though some of the mechanical details in the 

 construction of later object holders are better than in the original Schanze pat- 

 tern. The most important improvements in the object holder are represented 

 by those which are embodied in what is familiarly known as the Naples holder, 

 which is now used in many of the best microtomes. 



To recapitulate, we find that the mechanical movement of the object to be 

 cut was first introduced in an available manner by His and Ranvier ; that the 

 mechanical movement of the knife was first employed by Rivet, but the success- 

 ful employment of metal in instruments with a mechanical movement of both the 

 object and the knife was first adopted for the instruments made by Leyser, 

 under the direction of Brandt ; and, finally, that in the microtome made by 

 Schanze we have an object holder with adjustment around two horizontal axes 

 and revolution around a vertical axis, also a combination of the mechanical 

 movement by means of the micrometer screw with mechanical movement of the 

 knife. The three essential things which appear as the product of these early 

 inventions are, therefore, mechanical movement of the object, mechanical move- 

 ment of the knife, and mechanical adjustment of the plane of the section. These 

 three fundamental requirements must be met by every microtome which aims to 

 fulfill our present demands. 



We thus see that after several preliminary inventions have been introduced, 

 there come four instruments : that of Ranvier, of Rivet, of Leyser, and of 

 Schanze, which together represent all the essential features which have been 

 followed in the construction of microtomes, until we get to the introduction of 

 the automatic instruments which involve new principles. All further accounts, 

 therefore, must first review the history of the modifications of, and the develop- 

 ment of the accessories to, the types of microtome indicated in the preceding 

 descriptions. After that we shall recur to the history of the automatic micro- 

 tomes and the modifications which have gradually occurred in them. 

 Harvard Medical School. Charles Sedgwick MinoT. 



