CHAPTER XVII 

 RECONSTRUCTION OF OBJECTS FROM SECTIONS 



In investigating objects which possess complex internal cavities 

 or complicated structures, it is frequently very difficult to gain an 

 adequate idea from the direct study of serial sections, or by means 

 of macerated or teased preparations, consequently, various methods 

 of plastic or geometrical reconstructions from the sections are 

 resorted to. For such reconstruction, sections must be of uniform 

 thickness, serial, and they must possess similar orientation. 



RECONSTRUCTION IN WAX 



Bern's method of constructing wax models of objects from 

 serial sections is widely used for both embryological and anatomical 

 subjects. The thickness of the sections, the magnification of the 

 microscope, and the plane of section must be known. 



Wax plates are prepared as many times thicker than the actual 

 sections as the latter will be magnified in diameters. For example, 

 if the serial sections are ^ of a millimeter thick (33^ microns), 

 and they are to be magnified 60 diameters, then ;the wax plates 

 must be made 60 times as thick as the sections, or 2 millimeters 

 thick. This is the thickness commonly used. Count the number 

 of sections to be reconstructed, and prepare an equal number of 

 plates. 



Preparation of the Wax Plates 



(a) The original method. 1. To prepare wax plates of the proper 

 thickness (2 mm.) use several straight-walled rectangular tin pans 25 mm. 

 deep and measuring 270x230 mm. in area. 



2. In order to make the beeswax which is to be used flexible, add a 

 little turpentine to it. The specific gravity of the mixture will be about 

 0.95, and the weight necessary to make a plate of wax 2 mm. thick in one 

 of the pans will be about 118 grams. 



3. Fill one of the pans with boiling water to the depth of about 

 1.5 cm., melt 118 grams of the prepared wax and pour it upon the water. 

 The wax should spread evenly over the surface, of the water if both wax 

 and water are sufficiently hot. If gaps remain, close them by drawing a 



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