152 



BROWN, ON MICROSCOPICAL MANIPULATION. 



with the fibroid appearance of the sheath. This is very 

 strikingly brought out by the difference of tint, in the pro- 

 duction of which it must be remembered the carmine has to 

 soak through the medullary sheath, before it can possibly 

 reach the axial cylinder. The former is thus placed in a 

 position most favorable for being tinted by the colouring 

 material, did it possess any attraction for it. This is not, 

 however, the case. The latter alone receives the tint. By 

 this process the continuity of the axial cylinder along a 

 lengthened portion of nerve-fibre, as long in fact as can con- 

 veniently be placed upon the glass slide, may satisfactorily 

 be traced. As one looks at a preparation of this kind, the 

 comparison between the nerve-fibres in a bundle, each axial 

 cylinder of which is invested by its own medullary sheath, 

 and the various strands of an electric cable, each wire of 

 which is surrounded by its independent insulating invest- 

 ment, almost involuntarily suggests itself. ■ 



Upon Microscopic Manipulation. By Henry Hort 

 Brown. M.R.C.S.L. 



In preparing and mounting objects for the microscope, so 



much of successful manipulation depends upon system and 

 order in the detail of operations, that I have ventured to 

 record some few appliances I have from time to time invented, 

 with a view of obtaining more uniformly successful results 

 in this branch of science. 



The " mounting board" that 1 use is of f-inch piue, 21 

 inches long by 7 inches broad, made according to the 

 accompanying plan (which is on a scale of] inch to the foot). 

 The central space (1) is for holding the necessary tools for 



