344 SUMMARY OF CURRENT RESEARCHES RELATING TO 



liqnid and placed on blotting-paper, so as to withdraw much of the 

 alcohol. A drop of collodion having been put on a glass plate, it 

 is placed in it ; and the plate is laid horizontally into a flat vessel, 

 which is slowly filled with spirit ; after a few minutes the animal 

 adheres sufficiently well to allow of the glass being set vertically. 

 When large objects, such as star-fishes, are being set up, it is sufficient 

 to put drops of collodion at various points on the glass. One great 

 advantage of this method is that the collodion remains transparent 

 in spirit. 



Purifying and Hardening Commercial Paraffin.* — A method 

 for purifying and hardening commercial paraffin is recommended by 

 Dr. A. Fottinger. The parafSn is heated in a sand-bath with dis- 

 tilled water to which a small quantity of solid caustic potash has 

 been added. When the paraffin has melted and the potash is entirely 

 dissolved, the mixture is well stirred. After a certain time there is 

 an abundant precipitate ; this is allowed to settle, and the paraffin 

 is then poured off, thoroughly washed with distilled water, and then 

 heated afresh ; but this time the temperature must be considerably 

 raised, and kept high for several hours. If the paraffin turns yellow 

 it must be washed with a warm weak solution of caustic potash. This 

 method gives a white, very hard, and quite homogeneous paraffin, in 

 which there is no solution of continuity. 



Bleaching the Arthropod Eye. — Prof. Grenacher, according to 

 Prof. J. Carriere,f employed the following mixture (as well as one 

 with nitric acid) : — Glycerin, 1 part ; alcohol (80 per cent.), 2 parts ; 

 and hydrochloric acid, 2-3 per cent. The preparation remains in 

 this mixture until the pigment changes colour and becomes diffuse. | 



Separating the Layers of the Wings of Insects.§ — Mr. G. 

 Dimmock separates the two layers of the wing of Attacus cecropia by 

 the following process : — The wing from a specimen that has never 

 been dried is put first in 70 per cent, alcohol, then into absolute 

 alcohol, and from the latter, after a few days' immersion, into tur- 

 pentine. After remaining a day or two in turpentine, the specimen 

 is plunged suddenly into hot water, when the conversion of the 

 turpentine into vapour between the two layers of the wings so far 

 separates these layers that they can be easily parted and mounted in 

 the usual v^ay, as microscopical preparations on a slide. 



Method of Bleaching Wings of Lepidoptera to Facilitate the 

 Study of their Venation. || — In the common method of destroying 

 the scales on the wings of Lepidoptera, for the purpose of studying 

 tlieir venation, by means of caustic alkaline solutions, there is danger 

 of not arresting the action at the proper moment, and consequently 

 of destroying not only the portions which it is desirable to remove, 

 but also the scale-supporting membrane, and even the delicate veins 

 themselves. An application of a modification of the chlorine bleaching 



* Arch, de Biol., vi. (1885) pp. 115-25. 



t Carriere, J., ' Die Sehorgane der Thiere,' 1885, p. 205. 



X Amer. Natural., xx. (1886) pp. 89-90. 



§ Ibid., p. 92, from Psyche, 1884, p. 170. || Ibid., pp. 201-5. 



