XVII, 2. Wilson: A new System of obtaining directing-marks. 169 



A new System of obtaining 



directing-marks in microscopical sections for 



purposes of reconstruction by wax-plate moclelling. 



By 

 J. T. Wilson, 



Professor of Anatomy, University of Sydney, N. S. W. 



In most cases where many metliods have been proposed for 

 the accomplishment of the same object, it may be taken as tolerably 

 certain tliat none of the procediires advocated are siifficiently free 

 from objection to entirely displace rival Systems. 



Numeroiis plans have been put forward for the production of 

 reliable directing-planes and directing-lines in paraffin blocks for 

 sectioning, since the first introduction of Born's System of wax-plate 

 modelling-. And it is no doubt true that, if the details of these 

 methods be carried out , a correct result will , in most cases , be 

 attained. 



Objection may, however, be taken to each of these methods in 

 turn from some particular point of view. Some of them suffer from 

 lack of aceuracy ; some only aim at a partial attainment of the end 

 in view, i. e. of a complete graphic reconstruction; others are ap- 

 plicable only to special cases ; whilst others, scientifically conceived, 

 and capable of great aceuracy, are somewhat cumbrous, diflicult and 

 tedious, requiring not only special apparatus of more or less delicate 

 construction but not a little dexterity in manipulation. 



The present writer is not presumptuous euough to suppose that 

 the method he is about to describe is destined to displace all others, 

 and to solve the problem of combining in one method the desiderata 

 of aceuracy and reliableness together with simplicity, convenience 

 and rapidity. 



Yet is seems to him that the method now presented offers 

 certain advantages , more especially to the unsophisticated worker, 

 which Warrant its publication, in the hope that beginners like him- 

 self in the work of plastic reconstruction may have some of their 

 difficulties at least minimised. 



