1890.] Microscopy. 99 
Kastschenko’s Apparatus.'—Apparatuses planned to assist in 
processes of plastic reconstruction have been devised by Dr. N 
Kastschenko, which may be profitably used in preparing the paraffine 
block for ordinary ribbon cutting. 
The original apparatus had for its object to pare down the sides of a 
paraffine block in such a way that some geometrical pattern might sur- 
round the object. This pattern or ‘‘ definition line’’ was intended to 
facilitate the reproduction of the object in a magnified model from 
sections made. 
From the author’s point of view, of course it is important that the 
definition or boundary surfaces (which in a section of the object are seen 
as definition or boundary lines) should be perfectly parallel, or at any 
rate have a fixed and determined position. The apparatus which he 
advocates is intended to effect this. The two models were constructed 
for the Thomas-Jung and for the Spengel-Becker microtomes. They 
are shown in Figs. 1 and 2, their natural size. (Plate III. 
In Fig. 1 is shown the cutter or parer as constructed for the Thomas- 
Jung object-holder. It may, however, be fitted to any microtome with 
a cylindrical object-holder. Its construction is extremely simple. It 
consists of a stout ring 4, the internal diameter of which is exactly 
equal to that of the object-holder. The ring is immovably united to 
the piece æ, which in its turn is exactly like the paraffine cylinder 
which fits into the object-holder. In the ring is seen the binding screw 
¢. The paraffine-holder d, which fits inside the ring, may be either 
solid or hollow. 
The holes in d and a are for the purpose of turning round the appa- 
ratus. While the object is being pared down the part æ is fixed firmly 
in the object-holder, and when the block has had its definition-surfaces 
thus prepared, it is removed from the cutter and fixed on the object- 
holder in such a way that it is cut in a direction perpendicular to the 
surfaces. 
The second model (Fig. 2), represents an apparatus intended to be 
used in any ordinary object-holder, and is of such dimensions that 
movement in any direction when it is fixed in the clamp is possible. 
This ‘‘ parer ” fits into the apparatus ¢, which consists of two blocks of 
wood loosely united by short metal wires. The wooden holder of 
course fits into the clamp while the block is being shaved down. 
When the boundary surfaces have been satisfactorily adjusted to the 
block, the latter is removed from the ‘‘ cutter” or parer, and 
inserted into the wooden holder wherein it is sectioned. 
1 From an abstract in the Journal of the Royal Mic. Society, February, 1889. 

