46 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. lv. 



Methods of Differential Nucleolar Staining. 

 By Gustav Mann. 



As far as I am able to ascertain, Guignard'"' was the 

 first to describe a differential nucleolar stain by a certain 

 mixture of methyl-green and fuchsin, but he does not specify 

 any proportion of admixture, though he repeatedly mentions 

 the fact of the differentiation. I am unaljle to follow him in 

 Ids method, and, notwithstanding many trials have failed to 

 get his differential . stain, namely, the chromatin-elements 

 of the nucleus green and the nucleolus red by means of 

 methyl-green and fuchsin. 



While endeavouring to stain the nucleolus and indo- 

 nucleolus differentially, my attention was drawn by Dr 

 Macfarlane to heliocin as a good nuclear stain for Spirogyra. 

 By extending its action in combination with aniline-blue to 

 other tissues, I have succeeded in obtaining an excellent 

 differentiation : — 



Method. — Tissues, both vegetable and animal, preferably 

 fixed by my picro-corrosive method,t are treated for ten 

 minutes in a saturated solution of heliocin in 50 per cent, 

 alcohol, the sections are then transferred for from five to 

 fifteen minutes to a saturated watery solution of anilin-blue. 

 The superfluous stain is rapidly washed off by distilled water, 

 and the sections placed again for one to two minutes in the 

 heliocin-solution, dehydrated, cleared by resinified turpentine, 

 and mounted in turpentine-balsam. 



Effect. — The whole of the cell and the nucleus blue, 

 the nucleolus red. In karyokinetic figures the cell and 

 nuclear barrel are stained blue, the nuclear plate, monaster 

 and diasters stained red.:]: 



The chemical constitution of tlie heliocin 1 used I am 

 unable to find out ; when dry it is a brick-red powder, 

 readily soluble in water, slightly so in absolute alcohol, and 

 in each case showing no fluorescence. A watery solution is 



* Ann. Sc. Nat., si'r. 6, vol. xx. p. 318. 



+ See Trans. Bot. Soc. Ediii., vol. xviii. (1890) p. 4.32. 



+ I may state that in dividinf^ colls of tlie root of Nymj)haxt alba, we may 

 fitain the whole of the cell pink, and the nuclear plate, monasters and diasters 

 blue, by treating sections lirst with alcoholic eosin and tlien with alcoholic 

 methylene-blue. 



