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Journal of Applied Microscopy 



should call a section. According to our present standard, such a section would 

 be very clumsy and thick, and indeed our students are now so accustomed to 

 the perfect work of the microtome that most of them probably would scoff at 

 such sections as can be obtained with Valentine's knife. Nevertheless, it was 

 an instrument of great service and was employed successfully in the investiga- 

 tions, which laid the foundations of modern histology. 



Fig. 1. — Valentine's Double Knife. 



There followed after this a series of devices for the obtaining of sections. It 

 seems hardly worth while to attempt to look up all of these, for they are hardly 

 more than matters of curiosity. It will suffice to refer to Prof. Victor Hensen's 

 " Querschnitter," which was described in Vol. II of the Archiv fi'tr Mikroskop- 

 ischc Anatomic. This instrument was designed for making the sections under the 

 microscope and submit them to immediate examination in a fresh state. Men- 

 tion may also be made of the instruments designed respectively by Oschatz and 

 Welcker. None of them were of a sufficiently practical character to come into 

 general use. 



The first microtome of which I have any knowledge, and which corresponds 

 at all in principle to those now in use, is that which was designed by Prof. W. 

 His, and described by him in 1870 in the Archiv fi'tr Mikroskopische Anatotnie, 



Vol. VI, page 229. This instrument seems to me 

 worthy of attention, and I therefore give the figure 

 (Fig. 2) and brief description of it. Its most 

 essential parts are the object holder, moved 

 in a fixed plane by means of the micrometer 

 screw, and a plate of metal at right angles 

 to the plane of the object holder to guide 

 the knife. As will be seen by the illustration, the 

 instrument was mounted upon a little stand and 

 was placed at an inclination, so that in the actual 

 cutting the section made lies somewhat on the 

 blade of the knife. The object rested on the 

 plate so that the edge of the knife passed through 

 the object down to the plate itself, an operation 

 which, of course, was very likely to injure the 

 edge of the knife. But the knife itself was 

 guided and the object was moved mechanically, 

 so that in this instrument of Prof. His's we find already two essential con- 

 ditions, which must govern every microtome, a mechanical precision in the 

 movement of the knife and the mechanical regulation of the " feeding " of 

 the object to be cut. All that subsequent microtomes have accomplished has 

 been to attain these two objects more perfectly, to make the instrument more 

 convenient, and to add such devices as make it possible to work it automatically. 



Fig. '1. — His's Microtome. 



