554 SUMMARY OP CURRENT RESEARCHES RELATING TO 



Staining for Microscopical Purposes.* — In continuance of his 

 former articles, Dr. II. Gierke gives a tabular account of (1) the ixsc 

 of anilin dyes for ordinary and bacteriological investigatious ; (2) the 

 differentiation of tissue-elements by the reduction of silver salts, espe- 

 cially nitrate of silver ; (3) impregnation of tissues with chloride of 

 gold, and chloride of gold and potassium ; (4) treatment with osmic 

 acid. 



Staining Technique. f — For studying cell-division and bringing 

 out nucleoli, Dr. W. Flemming hardens the fresh tissues in the fol- 

 lowing mixture : — Chromic acid (1 per cent.) 15 parts ; osmic acid 

 (2 jier cent.) 4 parts ; glacial acetic acid 1 part, or less. The pieces 

 remain therein two to three days for complete hardening. They aro 

 then washed in water, and, for cutting, further hardened in alcohol, 

 or cut under alcohol, and washed in water. They are then stained in 

 strong saffraniu solution and washed in absolute alcohol (with 0*5 

 per cent, hydrochloric acid). 



For staining the inner root-sheath of hairs, the sections are placed 

 for several hours to one day in picrocai'mine of medium strength, and 

 then for several hours in Greuaeher's logwood,! washed in water, and 

 mounted in glycerin or cloves. The fibrilla) of the connective tissue 

 are rose or red ; muscles, yellowish red ; all cell-bodies, similar ; cell- 

 nuclei, dark purple-violet; horny substance of the hair, picric yellow 

 (pale greenish in old chromic preparations) ; the inner root-sheath, so 

 far as it is horny, of a brilliant light-blue colour. 



As a simple method of staining cell-substance and other parts 

 yellow, treatment with an alcoholic solution of picric acid is re- 

 commended, after staining with logwood, alum-carmine, or other nuclear 

 stains. This can bo applied to specimens hardened in alcohol, bichro- 

 mate of i)otash, chi'omic, picric, or osmic acids. 



Susceptibility of the Different Tissues to Colouring Matters. §— 

 Prof. Ehrlich has obtained some physiologically important results 

 from investigations into the susceptibility of the different tissues to 

 colouring matters. 



When colouring solutions — in particular methyl-blue — were in- 

 jected into living animals, and then, with the utmost expedition, parti- 

 cular tissues were examined, interesting reactions of the living tissue 

 under the colouring materials would be perceived, which, in spite of 

 their rapid evanescence, revealed important facts which by other 

 methods were in part w^holly unascertainable, in part to be ascertained 

 only with difficulty. 



After the injection of methyl-blue, Prof. Ehrlich found in the 

 submiicous tissue of the tongue very numerous fibres and fibrous 

 reticula coloured intensely blue, which sent processes to the epithelial 

 formations, and it was easy to determine that these fibres were the 



* Zoitbclir. f. Wiss. Mikr., i. (188-1) pp. 372-408. 

 t Ibid., pp. 349-61. 



X Flemming, W., ' Zellsubstauz, Kern- und Zelltlieihing,' 1882, p. 383. 

 § Nature, xxxi. (1885) pp. 547-8. Ecport of I'rocccdings of I3crliu Physio- 

 logical Society, 27th Feb., 1885. 



