ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 519 



soda to 100 parts of distilled water, and passing chlorine through to satura- 

 tion. The action is indicated by the following formula : — 



2NaH0 + 2C1 = H^O + NaCl + NaClO. 



-The solution thus contains 7-45 per cent, of hypochlorite of soda. 

 During the passage of the chlorine it is necessary to surround the solution 

 with a mixture of salt and pounded ice, otherwise the temperature rises, and 

 chloride and chlorate of soda are produced. The more effectual the cold, 

 the greener is the colour of the fluid, but the greenness fades away by ex- 

 posure to light and with lapse of time. The decolorizing action is pro- 

 portional to the greenness of the solution, and is due to the presence of 

 chlorine, and also to the hypochlorite of soda, which bodies act in virtue of 

 their property of setting free nascent oxygen. 



Experiments made with the foregoing solution by Prof. C. V. Ciaccio 

 and Dr. G. Campari, on animal and vegetable tissues, have demonstrated its 

 perfect efficacy, not only with the colouring matter of leaves and plants, but 

 also with the pigment in the retina, in the chitinous investment of insects, 

 and in melanotic morbid products. Hitherto these last three examples have 

 been held to be unalterable. Specimens to be decolorized must first of all 

 be hardened in alcohol and chromic acid or its salts. 



Latham, V. A. — The Microscope and how to use it. X. 



[Injecting — contd.l 



Journ. of Microscopy, VI. (1887) pp. 102-11 (1 fig. and 1 pi.). 

 Unna, p. G. — Die Eosaniline und PararosanHine. Eine hakteriologische Farbenstudie. 

 (Eosanilin and Pararosanilin. A bacteriological staining study.) 



73 pp., 8vo, Hamburg, 1887. 



(5) Mounting', including Slides, Preservative Fluids, &o. 



Medium for clearing up Celloidin Sections.* — Dr. C. Weigert finds 

 that a mixture of xylol and carbolic acid is efficacious for clearing celloidin 

 sections stained with hsematoxylin or carmine. 



Three parts by volume of xylol are mixed with one part pure carbolic 

 acid ; and in order to be sure that water is absent from the mixture recently 

 burnt, sulphate of copper is added. The copper sulphate is placed at the 

 bottom of a 250 gram bottle, so as to form a layer about two cm. high. 

 The mixture is passed over it, and the two are shaken up together. After 

 standing, the clear fluid is decanted off. 



This mixture is found to clear riband sections taken from 80 per cent, 

 alcohol. It can only be used for carmine and logwood stained preparations, 

 for basic anilin dyes are decolorized or removed from the sections by it. 

 But for bacterial investigations, if the preparation be first stained with car- 

 mine. Gram's method, as used by Weigert, can be adopted, provided that 

 anilin oil be substituted for the carbolic acid in the clarifying medium. The 

 last method is, however, said to need improvement. 



Reagents for clearing Celloidin Sections for Balsam Mounting.^ — 

 Dr. J. van Gieson finds that the only satisfactory reagent for clearing sec- 

 tions imbedded in celloidin is 01. Origani Cretici, or Spanish hopfenoel. 

 This clears rapidly, even in moist weather, after dehydration in 95 per cent. 

 alcohol. It is free from acid, and does not fade the Weigert hsematoxylin 

 stain if the preparations have been hardened for a long time in Miiller, and 

 are mounted in thick balsam. It is also good for Gram's method, the 



* Zeitschr. f. Wiss. Mikr., iii. (1886) pp. 480-81. 

 t Amer. Mon. Micr. Journ., viii. (1887) pp. 49-51. 



