238 The Microscope. 



of Micro-botany, of the British Museum, and H. Morland, of London, 

 A lengthy space would be required in which to detail the special 

 lines of work in which the gentlemen named above have distinguished 

 themselves ; but all concur in adding lustre to the research and study 

 of the Diatomacefe or Foraminifera, as shown in the beautiful results 

 attained by them. 



While abroad, I secured a collection of the finer diatom prepara- 

 tions showing the skill of some of the parties already referred to. 

 Herr Rudolf Getschmann, of Rixdorf, near Berlin, with whose pre- 

 parations I am most familiar, proceeds in their preparation after the 

 following method, which he demonstrated before me. A table is 

 arranged before a well lighted window, and on this is placed the 

 requisite appliances for work. The chief requisite being' a small 

 dissecting microscope, fitted with simple achromatic lenses, varying 

 in their focal length as the case might require, but a lense of about 

 a quarter-inch focus answering for actual work. Preparatory to 

 beginning a selection of diatoms for the design to be arranged, a 

 quantity of cleaned diatom material is evenly spread over an ordinaiy 

 slide, this is carefully examined, and from it is selected all the per- 

 fect forms likely to be used in a design, anS transferred to a cover- 

 glass; all forms of the same shape being grouped together, or 

 arranged in lines for convenience afterwards; if necessary, several 

 cover-glasses can be thus filled with perfect forms, free from cracks 

 or other blemishes, and placed aside, protected from dust until 

 required. The diatoms are picked out from the spread layer of 

 material, by the aid of hair bristles of varying degrees of fineness 

 mounted in a slender wooden handle, and projecting therefrom about 

 a half inch; the bristle should be straight, and, if possible, have a 

 fine taper to a sharp point, this is handled, or used, with a free and 

 steady hand, and, to facilitate steadiness in picking out, the two arms 

 are rested upon two cushioned blocks of wood, tapering from the 

 level of the stage of microscope to their bases on table. A further 

 indispensable piece is a glass slide, having an area at its center of 

 about a quarter of an inch, or somewhat less, ruled into minute 

 squares, at the rate of about forty lines to the quarter inch; on this 

 slide, and properly centered, must be placed the cover-glass upon 

 which it is desired to produce the group. The cover-glass is pre- 

 pared by spreading at its center a minute drop of liquid gelatine by 

 means of a little brass spatula, and allow to dry. A number of 

 cover- glasses, after having been carefully chosen and thoroughly 

 cleaned, might be prepared and also set aside for use later. The 

 clear and transparent gelatine should be filtered before use, by pass- 



