732 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



tance by post, the preparation of them should be stopped after they 

 have been in spirits of wine on the film of Canada balsam. The film, 

 with the insect on it, can be detached from the piece of glass by cut- 

 ting the former with the point of a fine needle drawn round the insect. 

 Remove the detached piece of film and place it in a small glass bottle 

 full of clean spirits of wine. The hardened balsam can at any time 

 be dissolved away from the insects by spirits of turpentine. It is 

 sometimes easier to set small insects in position by placing them on 

 their backs upon the film of balsam. Their legs can be arranged in 

 that position with greater facility. 



Fluid for Preservings' Delicate Crustacea and Ccelenterates.*— 

 Dr. F. C. Noll has found a fluid which is very suitable for permanent 

 preparations of delicate Crustacea and their larvae, preventing their 

 shrinking or becoming too transparent. 



It is a mixture of equal volumes of Farrant's medium and Meyer's 

 fluid No. II. It is never cloudy nor entirely dry, although it has 

 such a consistency that air-bubbles scarcely ever occur. The prepa- 

 ration is sealed with asphalte or some other varnish. In order to pre- 

 vent cracks arising in the asphalte varnish, it is better after a time to 

 pass over it a layer of transparent shellac."!" 



Hydroids, small medusfe, and other ccelenterates which have been 

 hardened in alcohol and then stained, may, the author says, be splen- 

 didly preserved in the above fluid. 



Hertwigs' Macerating Fluid-I — For the isolation of tissues in the 

 Ccelenterates, 0. and E. Hertwig recommend the following mixture : — 

 Acetic acid, 1 part ; osmic acid, l-5th part ; sea water, 1000 parts. 



By means of this fluid not only the nerve-cells, muscle-cells, &e., 

 can be isolated so that the exact form of the individual cells may be 

 easily recognized, but also the tissues in the form of thin lamellfe 

 may be separated and studied as a whole. Pieces of tissue or whole 

 animals ai-e left in the mixture five to ten minutes, and then washed 

 for several hours in l-5th per cent, acetic acid. The macerated 

 parts can be further prepared, and afterwards coloured on the slide ; 

 or they can be coloured at once before preparation with needles. In 

 the first case picrocarmine is used, in the second Beale's carmine, 

 because it does not harden the tissues, but assists rather the process 

 of maceration. Pieces of tissue may be preserved a long time in 

 glycerine diluted with an equal volume of water, provided a few 

 drops of carbolic acid have been added to secure against mould and 

 Bacteria. 



To obtain preparations of single cell-elements of Actinice, the 

 macerated portion nmst be carefully divided up into smaller parts by 

 needles, and one or more of these parts placed under the cover-glass. 

 Light blows on the cover-glass with a needle will cause the cells to 



* Zool. Anzeig., vi. (1883) p. 472. 



t " Mit einer Lage des durchsichtigen Schutzlei3ten-(Schellack-)Kitts, wie 

 ihn die Hirscb-apotheke in Frankfurt a. M. licfcrt." 



X Jen. Zeitschr. f. Naturwiss., xiii. (1879) p. 4G2. Cf. Amcr. Natural., xvii. 

 (1883) pp. 80G-7. 



