ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
265 
be rotated by the projecting handle on the right between two screw 
points in tho ends of a powerful clamp fastened to the projecting edgo 
of the table. From the upper end of the bar projects a horizontal arm 
carrying a clamp in which the short knife is held by two screws. In 
front of the knife and supported by a plate projecting from the base- 
clamp is a metal cylinder, in which a second cylinder, holding the pre- 
paration, is raised by means of the micrometer screw. Jung offers two 
instruments, differing only in the method of raising the cylinder : in the 
one the screw is simply adjusted by touch as in the English original, 
while in the other, represented in the figure, there is an automatic 
adjustment of the micrometer screw which, though simple in construc- 
tion, works satisfactorily. The displacement is effected by a pall 
engaging in a toothed wheel, and its amount, ranging from 10 to 100 /z, 
is regulated by an adjustable plate provided with a division. The knife 
is set square and is on the radius of a circle having the axis of rotation 
as centre. Thus the different parts of the knife will move with different 
velocities, and as a result there is a displacement of the object towards 
the parts nearest to the axis of rotation ; but this effect is so slight as to 
be scarcely appreciable. The movement of the knife is very smooth and 
regular. The lower of the two screws about which the guiding bar 
rotates can be adjusted when, after prolonged use, the points of the screws 
have penetrated deeper and deeper into the bar. The instrument is not 
intended for very delicate work, but for ordinary useful sections of 
paraffin and frozen preparations. 
The second microtome described is a slightly modified form of the 
“ Cambridge rocking microtome,” which was described and figured in 
this Journal, 1885, p. 550. The instrument produces sections which are 
not simply plane surfaces, but portions of a cylinder with radius equal 
to the distance of the knife-edge from the axis, and therefore cannot be 
used for most embryological investigations. Its chief use is for paraffin 
preparations of histological objects. The author remarks that the 
instrument can be used with advantage by the pathological anatomist in 
nearly all cases, but by the normal anatomist only in a restricted degree. 
Minot’s Microtome.* — Herr P. Schiefferdecker describes a new and 
improved form of Minot’s microtome.! On a metal plate supported by 
short feet rises a strong upright A (figs. 32 and 33), which carries a slide- 
way provided with a swallowtail groove. In the figure this is raised so 
high that it reaches the end of the upright ; it carries a second horizontal 
slide-way in a swallowtail groove, which is moved by a micrometer- 
screw having at its end the large toothed wheel B. This slide carries 
on the end turned towards the knife a disc, to which the paraffin pre- 
paration is attached. This disc can be turned in different directions by 
the hand and fixed in any desired position by screws. In the large 
toothed- wheel B engages a pall which is attached to a movable metal 
plate fastened to the vertical slide- way. This metal plate pi ejects 
beyond the pall, and the free end, by the vertical movement of the slide 
presses against one of the six rays of the star at the side. The pall is 
thus drawn down and consequently rotates the toothed wheel, by means 
of which the preparation is displaced. The different rays of the star 
* Zeitschr. f. wiss. Mikr., ix. (1892) pp. 176-9. f See this Journal, 1889, p. 143. 
1893. T 
