172 SUMMARY OF CURKEXT RESEARCHES RELATING TO 



all, may not exceed 0-2 mm. Although firm in consistence, they are per- 

 fectly flexible, and are cut with sharp knives or scissors quite easily. 



The author mentions also a mixture of gum-tragacanth, sugar and flour, 

 as capable of being rolled out into very thin plates, but does not indicate 

 the proportions of the ingredients. 



(5) staining and Injecting:. 



Rosanilin Nitrate for Goblet and Mucous Cells.*— Dr. J, H. List now 

 uses a O'OOOl per cent, of rosanilin nitrate for goblet and mucous cells. 

 Sections taken fi'om 50 per cent, alcohol are overstained in the above fluid 

 for ten to fifteen minutes. The superfluous stain is then extracted in abso- 

 lute alcohol. The nuclear structure, as well as the reticulum of the cell, are 

 well shown. After hardening in chrom-osmium-acetic acid, the chromatin 

 of the nucleus comes out extremely well. The karyokinetic figures in 

 epithelium are also well shown. 



Absorption of Colouring Matters by Plants. t — Dr. TV. Pfeffer, as pre- 

 viously recorded, 1 has discovered that certain anilin colours are taken up by 

 living cells and eventually assimilated. It is possible, therefore, that these 

 dves may be used to study the processes of absorption. If, for example, 

 Trianea hogotensis is placed in a O'OOl to 0*002 per cent, solution of 

 methylen-blue, the cells of the root-hairs will be found, in a few hours, to 

 be stained a deep blue, while blue granules are discerned in the cells of the 

 root-epidermis. The solution must not be too strong as a poisonous eftect 

 is produced on the plant. Assimilation of methylen-blue takes place when 

 plants are left in a solution of one part methylen-blue to ten million parts 

 of water. The pigment may bo removed without damage to the plant by a 

 • 01 per cent, solution of citric acid. 



Methyl-violet, cyanin, fuchsiu, methyl-green, Bismarck brown, are taken 

 up to some extent, nigi'osin and aniliu-blue not at all. 



Methyl-violet and cyanin stain the cell-protoplasm without damaging the 

 life of the cell, and the blue staining of the protoplasm by cyanin demon- 

 strates also the alkalinity of the protoplasm. 



Relation of Fatty Matter to the Receptivity of Staining in Micro- 

 organisms.§ — Dr. A. Gottstein after treating sections and cover-glass pre- 

 parations with fat-dissolving reagents (heating the preparations with caustic 

 potash in alcohol 2-5 per cent.), finds that tubercle bacilli, treated by the 

 Ehrlich method, give the characteristic reaction, while smegma bacilli lose 

 their acid-resisting property when manipulated in a similar manner. The 

 author remarks that while ordinary fats lose their anilin staining after the 

 action of an acid, lanolin, like cholesterin and certain fat-crystals (Celli's 

 and Guarnieri's pseudo-bacilli) presents a similar resistance to acids, as do 

 tubercle bacilli ; hence smegma bacilli probably retain their staining 

 capacity from the presence of a body analogous to lanolin. 



Phloroglucin Test for Lignin.|', — Herr A. Tschirch finds the applica- 

 tion of phloroglucin-hydrochloric acid a very useful test for the degree 

 of lignification in wood ; or, since the bark of most Angiosperms contains 

 phloroglucin, hydrochloric acid alone may frequently be used. In this 

 way it is shown that the bracheids are much more strongly lignified than 

 the stereids in a " mixed ring," % the former taking at once a dark-red 



* Zeitschr. f. Wiss. Mikr., iii. (1886) p. 393. 



t Bot. Ztg., xliv. (ISStJ) pp. 114-25. ; See this Journal, ISSC, p. 638. 



§ Fortsclir. d. Med., iv. (1886) p. 2J2. 

 11 Pringsheim's Jahrb. f. Wiss. Bot., xvi. (1885) p. 325. 

 ^ Cf. tljis Journal, 1SS6, p. 1008. 



