ON STAINING FLUIDS, AND STAINING. 129 



The " Thoma Microtome " adapted equally for 

 the paraffin embedding and ether freezing processes, 

 is an exquisitely beautiful and reliable instrument. 

 The preferable size for ordinary use is that named 

 the Thoma B. 2. A verbal description would be of 

 but little use, and the author advises the student 

 to see one, and this he can (generally) do on applica- 

 tion to Mr. C. Baker. Its manufacturer, Mr. R. 

 Jung Mekaniker, Heidelberg, will send a full 

 (illustrated) description on application. 



Minot's Microtome. 



This beautiful instrument is made in three forms 

 (or to use the inventor's expression, " models "). 



In its construction the chief endeavour has been 

 to render its various parts as " massive " as possible, 

 and to make the adjustments for the various thick- 

 nesses of the sections perfectly automatic, whilst, 

 at the same time, portability has been considered. 

 The thickness of the section is regulated by a special 

 toothed wheel arrangement. On the ascent of a 

 vertical slide a lever strikes one of the six spokes 

 of a wheel, and the ratchet turns the toothed wheel 

 of the micrometer screw so that the horizontal slide, 

 to which the preparation is attached, is brought into 

 contact with the edge of the knife. The six spokes 

 of the controlling wheel are of different lengths, 

 and are marked 1 to 6, which numbers correspond 

 with the number of teeth on the wheel moved at 

 each revolution of the driver. 



In Model I. the total number of teeth is 150, and 

 as one complete turn of the micrometer screw equals 

 0*5 m.m., by means of the spoked wheel sections 

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