98 The American Naturalist. [January, 
MICROSCOPY." 
Certain Improvements in Born’s Method of Reconstruct- 
ing Objects from Serial Sections.—The original method of Dr. 
Born was treated with considerable detail in Vol. XVIII., 1884, of the 
NATURALIST; since which time several improvements have been 
effected, descriptions of which have appeared from time to time. We 
take the following from a recent number of the Zeztsch. für Wiss. Mikr., 
VoL V i 
The block of paraffine holding the carefully imbedded object should 
be cut into as perfect a prison as possible, the use of special instruments 
for this process being recommended. It is further advised that one of 
the faces at right angles to the plane of the knife should be marked in 
such a way as to leave no question as to its identity when the sections 
are cut. This marking may be brought about by the use of scoring, 
the lines being filled with coloring matter, and then covered in the 
ordinary way by dipping in warm paraffine. 
The sections should have a thickness of about 1-50 mm., and the 
paraffine should be so prepared that it will not crush or crack before 
the edge of the knife. ” 
The finally mounted sections are placed under the microscope, and 
by means of a camera the outlines are drawn to scale on separate 
pieces of paper. The thickness of each section and the amount of 
increase in size of the camera drawing over the original being known, 
it is a simple matter to determine the desired relative thickness of the 
wax that is to be applied to the paper bearing the drawing. 
_ The improved method of applying the wax is as follows : 
A lithographer’s stone having been brushed over with turpentine, 
the paper is evenly spread upon it, and a strip of metal of the desired 
thickness is placed along each side. Wax is now poured over the 
paper, and, by means of an iron roller, is pressed into a layer of equal 
thickness with parallel strips of metal, which at the same time support — 
the roller and limit the spread of the wax. The thicknesses recom- 
mended for the plates are 0.4, 0.6, 0.8, 0.9, 1, 1-12, 1-5, 1.8 and 2. a 
mm. Combinations of these will give a sufficient range of thicknesses 
to correspond with all ordinary sections, 
After the plates have all been made the careful work of removing the 
surplus wax should be undertaken, the drawing on the attached paper 
directing the work. Finally the enlarged sections are stuck together 
in their proper order, the model resulting. 
1 Edited by C. O. Whitman, Clark University, Worcester, Mass. 





