XIV, 1. Woodworth: Graphic reconstruction from serial sections. 17 



sides of the axial line, thus giving tlie diameter of section 23 multi- 

 plied one hundred times. By repeating this process for each section 

 and then joining the points thus obtained, there results a symrne- 

 trical outline at the desired scale , approximately like that of the 

 worra, all deviations in the object from the symnietrical shape, such 

 as lateral bends or indentations, being obliterated. It is convenient 

 to have the rulings of the ocular-niicrometer longer than they 

 ordinarily are, so that all parts of the section will fall inside 

 the lines. 



The outlines of the object having thus been fixed, to plot the 

 intestinal tract, or any other Organs, it is only necessary to inake 

 measurements from one margin of each section to the nearest and 

 farthest liniits of the organ desired in the reconstruction, multiply 

 the distance by 100, mark off the results on the corresponding 

 parallel lines, and join the points as before. Obviously, for the 

 forked intestine of a trematode four such measurements would be 

 needed 011 each of the sections behind the point where the intestine 

 bifurcates. It is to be noted that, although the distances are plotted 

 from one margin of a symmetrical outline of the animal , the pro- 

 jection of the outline of any organ , no matter what its position, 

 shape or course may be, is faithfully reproduced. 



The advantages of an ocular micrometer with extended rulings 

 are now apparent. In many cases the rulings in an ordinary oeular- 

 micrometer are not of sufticient length to embrace all organs which 

 it might be desired to show in the reconstruction; but with a plate 

 having the rulings of greater length, no matter in what part of 

 the field an organ may lie, its distance from the margin of the 

 section can be determined by the ruüngs, and thus any organ in 

 the section can be brought into the reconstruction. The micrometer 

 should also be provided with at least one line at right angles to 

 the rulings. 



As before stated, the method is best applicable to transverse 

 sections of bilaterally symmetrical objects, lateral irregularities of the 

 outline of the objects disappearing in the reconstruction. However 

 the method can also be employed with objects of any shape 

 or outline, if they can be provided with a plane of definition 

 at right angles to the plane of section. I have made use of it in 

 obtaining reconstructions of the sexual organs of Flatworms from 

 longitudinal sections , establishing a plane of definition by cutting 

 off one end of the worm by means of a Kastschenko's ..Uesehnei- 



Zeitschr. f. wiss. Mikroskopie. XIV, 1. - 



