ZOOLOGY AND BOTANY, MIOROSOOPY, ETC. 293 



two of water ; no more water should be used than is necessary. Cut 

 off the head and place it in a small porcelain saucer, and cover with 

 a little of the acid, which must be changed about every other day 

 for say a week, or until it ceases to become coloured. The tongue 

 will then, in most cases, be found to be protruded, or may be forced 

 out by slightly pressing the head. 



Expanding. — To expand the tongue, it should be placed in the 

 centre of a glass slip, and put upon a piece of wood about 5 in. by 

 1 J in., into one end of which a piece of wire has been inserted and 

 bent over to form a clip, the centre being covered with a circle of white 

 paper to form a light background. A piece of glass about 1 in. by 

 11 in., to be used as a pressor, is placed upon the glass and under the 

 spring, and is kept apart from the slip by several folds of paper about 

 the thickness altogether of the fly's head. The head, with eyes 

 uppermost, and the tongue protruded towards the right hand, is then 

 placed in a drop of acid under the edge of the pressor, and held there ; 

 and, if necessary, the tongue forced to protrude further by a slight 

 pressure of the forefinger of the left hand. While in this position, 

 the expander, a piece of glass 1 in. by f in., to the under side of 

 which a small cover-glass has been fastened by brown cement, and 

 having a piece of paper by which to hold it gummed to the top, is 

 used to force the lobes of the tongue backwards — that is, towards the 

 left hand, and downwards, into the required position. The palpi, 

 which will usually be found lying against the head, may then be 

 arranged by means of a stiff bristle, and the head laid aside for 

 three or four days to set. 



Mounting, — After cutting away the head, transfer the tongue, 

 which must be kept the same side up, to a drop of fresh acid on the 

 centre of a clean glass slip. This may be done by pushing it on to 

 the end of a quill which has been bent a little at the end, to form a 

 kind of spoon. Apply balsam at the right-hand side of the cover- 

 glass, and drain off the acid by holding a piece of blotting-paper to 

 the opposite edge. If any cloudiness appears, warm the slide a little. 

 A light clip may then be put on, and the slide put aside to harden. 

 No needles should be used in any part of the process. 



Preserving and Staining Protozoa.* — Dr. H. Blanc whilst re- 

 cognizing that the methods of j)reserving Protozoa are already 

 numerous, describes one which he has emj)loyed for a year and a half, 

 and which has given satisfactory results, without any loss of the colour 

 in Canada balsam. 



Ceftes and Landsberg use osmic acid ; Korschelt, chromic or 

 osmic acid ; Kleinenberg's picro-sulphmic acid (also used by Entz) 

 is employed by the author, compounded as follows : — Concentrated 

 picric acid, 100 vols. ; sulphuric acid, 2 vols. ; distilled water, 

 600 vols. This solution may be used as it is for preserving the 

 larvEB of Echinodermata, MedusEe, and sponges ; but for Ehizopoda 

 and Infusoria, add a little 1 per cent, acetic acid, two or three drops 

 to 15 cc. of liquid. The object of this addition is to bring out 



* Zool. Anzeig., vi. (1883) pp. 22-3. 



