250 



Modern Microscopy 



2. Jung's pattern (Pig. 68), in which the blade fits into 

 an ebony screw handle, is another useful form. It may be 

 used for cutting at right angles to the tramway, or obliquely 

 by means of a slicing cut — that is, if a knife of a suitable 

 size for the microtome is selected. Owing to the shape 

 of the handle supplied, these knives are fairly easy to 



Fig. 68.— Jttng's Microtome Knife with its Screw Handle. 



sharpen ; they are also usable upon several kinds of micro- 

 tomes, so that this pattern is an universal knife. It is fitted 

 to the microtome in the manner indicated in Fig 66. 



Weikert's and Thoma's Knives. — Two other patterns 

 frequently used are : Weikert's, with a straight handle and 



Fib. 69. — Weikert's Microtome Knife with Straight Handle. 



both sides of the blade concave — this is a useful tool for 

 cutting celloidin-embedded objects under fluid ; and Thoma's, 

 or the Heidelberg pattern, with a curved handle, which 

 has the under side fiat and the upper side concave. The 

 latter is of the same utility as the Jung pattern, but 

 does not require a special holder, as it fits directly to the 

 carrier of the microtome. Both these knives (Figs. 69, 70) 



