746 The American Naturalist. [August, 
MICROSCOPY. 
Schaper’s Method of Reconstruction.'—The ingenious method 
of reconstruction that has been described by Dr. Schaper has consider- 
able advantage over the older method of Born, now long a familiar one 
in embryological laboratories. The base line of the sections is not at 
a distance from the section of the object as in the old method, but, on 
the contrary, is in the edge of the section itself, so that it is always 
in view, even where the section is so large as to be scarcely included 
within the field of vision. And one may as safely say that it is fully, 
if not more accurate than the older method. 
Schaper first saturates the embryo with paraffin to prevent its drying 
and shrinking during the second stage of the process. In this second 
stage the embryo is taken from the bath and the superabundant melted 
paraffin removed from it by means of bibulous paper. It is then 
fastened by a drop of paraffin to a perfectly white piece of bristol-board. 
This forms a background from which the object stands out in sharp 
contrast, and allows of a good photograph being taken, or of an accu- 
rate outline sketch being made of it with a camera. The photograph 
or sketch is supposed to represent the natural size of the embryo. 
The object is then removed from the bristol-board and replaced in 
the bath. Next he draws a line on the sketch or photograph just touch- 
ing the dorsal outline and another one perpendicular to the first just 
touching the head, thus including the figure within a right angle. A 
similar right angle is drawn on a piece of cardboard that fits into the 
imbedding box. ‘The latter is filled with melted paraffin, and then 
with warm needles the embryo quickly and carefully arranged in the 
right angle to correspond as closely as possible with the position of the 
figure in the sketch. The usual process of hardening the paraffin Is 
then gone through and the object is ready for sectioning. 
Care is taken in sectioning to have the plane of sectioning perfectly 
perpendicular to the median plane of the embryo; and, of course, it 18 
assumed that the embryo is as straight as possible. The thickness of 
20 is chosen for the sections as the best, since in thinner ones the m- 
ternal structures are apt to be broken and thicker ones are not likely 
to be sufficiently transparent. Sketches of the magnified sections are 
made on paper, and these, or whatever portion of them may 
1 Schaper, A. (97), Zur Methodik der Plattenmodellirung. Zeit. Wiss. Mikros-, 
XIII, 4, 446-59. 
