ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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knife. The band arrangement is a roll of paper kept taut (figs. 22-25), 
and passing close to the edge of the knife. The roll P R passes first 
through a guiding loop ^K, which gives it its direction parallel to the 
object. It is kept in this position, and at the same time applied to 
the edge of the knife M, by the roller W, the diameter of which is 8 mm. 
The band, after leaving the space between roller and knife-edge, is di- 
rected upwards to the clamp v K, and there passes over another roller r, 
and to its end is attached a weight for the purpose of keeping the whole 
quite taut (fig. 23). In order to reduce the friction between the knife, 
the roller, and the paper band to the practical minimum, the roller W 
is made as small as possible (8 mm.), and the upper surface of the knife- 
edge is ground to an angle of 20°-25°. (See fig. 26.) The desired effect 
is thus obtained, and by using a paraffin of medium softness for imbedding 
the specimen, the sections show little tendency to break or curl up. 
When in actual use, the paper band requires to be removed from 
the surface of the paraffin block in order to let the knife be put into 
position for cutting again. (See figs. 22 and 23.) This done, the roller 
is replaced, and receives after each alteration the necessary tension from 
a spring. As the sections are cut they adhere to the under-surface of 
the band. The adhesion is effected by smearing the block surface after 
every section with a mixture of castor oil 3 parts, and 1 part collodion 
of double strength. The microtome is made in two forms, as shown in 
figs. 23, 24, and 25. 
In fig. 24 is seen a view from above of the simple construction for 
the cross position of the knife. In fig. 25 is a similar view of the more 
complicated apparatus, which allows the knife to be used in any position. 
Miehe’s Improved Lever Microtome.* — The lever microtome of 
Gustav Miehe, so called because the knife-carrier is fitted with a 
handle so that this piece may be easily worked, has been improved by 
the addition of a spring catch to the microtome screw-plate, so that 
every division of the plate, and therefore, of course, the rising or descent 
of the screw, is audibly clicked. 
The mechanism of the recent addition is simple. It consists in a 
catch m, held in its place by the spring n, which is fitted on the end of an 
arm o, locking in the teeth of the microtome plate. As the pitch of the 
* Preis-Verzeichniss von G. Miehe, 1889; Miehe’s Catalogue of Microtomes. 
