1248 General Notes. [December, 
blocks, which may be easily fixed, for cutting, to a larger block 
of hard paraffine, or better, to a block of wood saturated with 
paraffine. 
ORIENTATION WITH SMALL ObsjectTs.—Orientation becomes 
difficult only with objects so small that their position can be con- 
trolled only by the aid of a microscope. Spherical objects, less 
than one millimeter in diameter, z. g., many ova and embryos, 
are the most difficult to manage. Such objects may usually be 
successfully oriented in the following manner : 
I. Prepare the box; for this it will be necessary to use the two 
triangular pieces of metal, a rectangular glass plate (2 in. x 2% 
in.). The plate should be cleaned and then smeared with glycer- 
ine, and the pieces of metal so adjusted, that the arms are parallel 
with the edges of the plate. 
2. Having warmed the box over a spirit inin lift the object . 
from the basin of paraffine by the aid of a small, flat, thin spatula 
(first starting it from the bottom by shaking the paraffine a little), ` 
and allow it to flow with the paraffine carried on the spatula into 
e box. 
3. Then fill the box (5-6"™ deep) with the melted paraffine, and 
warm it a little over a spirit lamp, just enough to keep a// of the 
paraffine in a liquid condition for a few moments. Now place the 
box on the warm table of a dissecting microscope, and by the aid 
of a hot needle proceed to place the object in the desired position. 
As the object is illuminated from below, it can be easily seen, 
turned over, and moved about at pleasure. If the paraffine freezes 
before orientation is effected, it should be melted again as before, 
and the needle va be kept hot by repeatedly holding it in the 
flame of the lam 
The difficulty ‘of finding very small objects in a basin of paraf- 
fine will be very much lessened by keeping the paraffine free from 
dust, and the bottom of the basin (tin) scoured bright. A piece 
of emery cloth serves for polishi 
e necessity of re-warming the box of paraffine, which often 
arises in the above method, may be removed by using a hot bath 
on the table of the microscope. This bath should be a box of - 
convenient size (not over 2™ high), with top and bottom of glass, 
with an opening at one end for filling with hot water, and another 
s at the opposite end provided with a rubber tube and clamp, for 
<3 drawing off the water as soon as the object has been arrange 
__ PREVENTION oF BupBLes.—After the imbedding process has 
een carried thus far, there is still another danger to be carefully 
against. If the box is left to cool slowly in the air, 
sles are very likely to appear in the paraffine, which will 
s s obstacle in cutting. Profiting by Caldwell’s sug- 
| the box in water, one may avoid all such incon- 
p ffine a Poos around the object, so 
