636 
SUMMARY OF CURRENT RESEARCHES. 
of a screw-clamp it can be fixed to any table having a projecting edge. 
The glass plate allows of cutting in any direction. It can be readily 
removed for cleaning, and replaced by a hollow cylinder for sectioning 
by the ordinary methods of imbedding. The screw for the displacement 
of the preparation has a disc divided in hundredths of a millimetre and 
is provided with a catch which marks each displacement of a division. 
For the sectioning the razor is moved by hand. 
Large Microtome for Brain-sections.* — Dr. J. Pal describes a new 
microtome made by C. Reichert according to his design, with which he 
has succeeded in easily obtaining sections of both hemispheres of the 
human brain. 
The instrument (fig. 77) is mainly constructed on the same principle 
■as that described in Zeitsch. f. wiss. Mikr., i. (1884) p. 241, but differs 
from it by special arrangements which allow of sections being made 
through a whole brain under water. It is also double the size and of 
stronger make. The length of the slide is 50 cm., so that knives with 
a cutting edge of 36 to 38 cm. can be used. Objects with a diameter of 
from 12 to 13 cm. and a height of 10 cm. have been cut with the instru- 
ment. For cutting under water the tank W is provided; the deep 
•central portion of this is formed of a stout leather bag V. At the 
bottom of this bag there is a box through which the rod of the clamp 
passes. The tank can be emptied by means of the cocks v v' at both 
ends. The rod of the clamp is received by the clamp-holder, which is 
adjustable in all directions. The holder is connected with a very strong 
slide which is raised by a micrometer screw having a diameter of about 
18 mm. and pitch of 0*6 mm. By this screw the object can be raised 
15 mm., and consequently from 250 to 300 sections may be cut in a 
continuous series without further adjustment of the object. 
As soon as the micrometer screw has reached its highest position, 
the pawl sp (fig. 78) and the spiral spring at the back of the microtome 
are disengaged, the micrometer screw is screwed down, the object- 
carriage pressed outwards, and the object again raised up to the knife- 
edge, so that the operator can resume cutting without change of the 
plane of the sections. 
On the back stroke of the knife, the object is automatically raised 
by a certain amount within the limits of 0*005 mm. and 0*055 mm. 
To obtain thicker sections the automatic arrangement must be set in 
motion twice, when sections of a thickness up to 0*11 mm. may be cut. 
The knife-carriage, which is of specially heavy construction and 
slides on five points as in Reichert’s smaller microtomes, has, to prevent 
tilting, a double groove, and is pressed on the slide by a spring counter- 
plate. 
For moving the slide the driving belt arrangement seen in fig. 78 
is chosen. The crank shown in fig. 77 has been lately replaced by 
a fly-wheel (fig. 78). 
The knife is attached to the knife-carrier T (fig. 77) by the two 
screws s and s', and is fixed by the nut m. It is prevented from springing 
by the support st. The microtome can be used without the tank, as 
seen in fig. 78. 
* Zcitsclir. f. wiss. Mikr., x. (1893) pp. 300-4. 
