H. MORLAND ON MOUNTING DIAT0MACEJ1. 323 



never make anything of them, nor do I know they were ever 

 nsed, excepting on paper; but under any circumstances I 

 maintain there is not the slightest necessity for such bristles, 

 as I will undertake to pick up and transfer the largest or 

 smallest diatom (capable of being handled) by means of one of 

 the bristles I regularly employ. 



Another important piece of apparatus is my " mounting 

 slip," which I prepare as follows : — First I take care to select 

 if possible a flat 3" x 1* slip, as many slips are curved more or 

 less, but should there be the slightest curvature I arrange for 

 the hollow side being underneath. On the upper surface at 

 one end I attach an ordinary slide label and put the slide on 

 one of the late Dr. Matthews' turn-tables, taking note 

 of the position of the labelled end, as these turn-tables 

 are not always absolutely central with the slides, and the 

 " mounting slip ' whenever put on the turn-table at future 

 times, must always be placed as in the very first instance to 

 ensure correct centring. I now mark on the centre of the 

 slip a series of four concentric rings, the smallest being about 

 -J^ inch across, the next one i inch, the third fa inch, and, 

 finally, the fourth one § of an inch in diameter. These dimen- 

 sions are only approximate, a little larger or a little smaller 

 being quite immaterial. These rings are drawn with a mixture 

 of a little aniline, dissolved in gum, and are for the purpose of 

 enabling one to rapidly centre the slide when under the 

 mounting microscope. Over these rings, with the smallest 

 amount of balsam possible, I place a fa inch covering-glass, on 

 the upper surface of which are ruled two series of lines, ^J ¥ inch 

 apart, and crossing each other at right angles. These lines 

 cover a surface of about \ inch square, and are for the purpose 

 of guidance when arranging diatoms on a cover-glass ; they are 

 useful for enabling diatoms to be set square with each other 

 and at definite distances apart. 



The only other special tools which I have to describe are, 

 firstly, a piece of glass tubing, about \ inch bore and two inches 

 long, with one end opened out slightly, something like a tobacco- 

 pipe mouthpiece ; this I use for breathing on my glass covers in 

 order to attach them to my " mounting slip." Secondly, two 

 pieces of brass, one fa inch diameter and fa inch thick, the 

 other, one inch long, J inch broad, and ^ inch thick. On the 



Journ. Q. M. C, Series II., No. 23. 24 



