602 SUMMARY OF CURRENT RESE ARCHES RELATING TO 



glands of Droscra, auil especially in the processes which accompany the 

 afTifrcfation of protoplasm, the transport of water and nutrient substances, 

 and the absorption of nutriment by young seedlings out of the endosperm. 

 The i^hunomcua which accompany the movements in the leaves of 

 Mimosa cannot, in the opinion of the author, be explained by the expulsion 

 of pure water out of the cells of tho pulvinus, but only by the power of 

 extramcability of tho protoidasts. 



Tho cause of tho intrameability of protoplasts requires further 

 experiments for its determination. 



Albuminous reaction of Cell-wall.* — Herr A. Fischer disputes tho 

 validity of Wiesuer's and Krasscr's demonstrations f of the presence of 

 albumen in tho cell-wall, on tho ground that a red coloration with 

 Millon's reagent is by no means so certain a test for albumen as those 

 writers suppose. In tho leaves of many species of Bromeliacea3, ho 

 finds not only the epidermis, hypodcrma, and sieve-tissue, but all tho 

 vmlignified cell-walls, even those of the chlorophyll-tissue, coloured by 

 this reagent, the very same unlignified cell-walls being all coloured 

 deep-blue by chlor-zinc-iodide. The tint with Millon's reagent is not 

 precisely that produced by undoubted albiiminoids, but is rather pink 

 than scarlet or flesh-coloured. It is obvious that the red staining takes 

 place uniformly throughout the whole of the cell-wall, which would not 

 be tho case if it wero due to strands of protoplasm. Fischer finds, 

 moreover, that the red-staining with Millon's reagent docs not manifest 

 itself in very young tissues, as would be the case were it due to proto- 

 plasm, and concludes that it may probably be caused by tyrosin, or 

 some other jH'oduct of the decomposition of albumen. 



In reply to this criticism, Herr J. Wiesner remarks | that his object 

 has not been simply to demonstrate the presence of an albuminoid in 

 the cell-wall, but to sujiport tho view that, at all events up to a certain 

 jjeriod, tho cell-wall is a living constituent of the cell itself, deriving 

 that character from a proportion of protoplasmic substance which enters 

 into its composition. In support of this view, he does not depend only 

 on the reaction with Millon's reagent. 



To this Fischer again replies, § repeating his objections to Krasser's 

 and Wiesner's micro-chemical tests for tho presence of albuminoids. 



In a further communication, || Herr F. Krasscr comments on Klebs's 

 arguments on the j^resence of albuminoids in the gelatinous sheath and 

 cell-wall of the Zygnemaceaj, % which he considers not conclusive, 

 although the conclusion arrived at is probably correct. 



Pleochromism of coloured Cell-walls.** — According to Herr 

 H. Ambronn, there are two kinds of ploochroistic cell-walls; those 

 which are already coloured in nature, and those in which the colour is 

 brought out artificially. The former arc comparatively rare ; they 

 occur especially in the skin of some seeds, of which the pigment is not 

 in the cavity, but in tho cell-wall. The testa of Ahms precatorius fur- 

 nishes a good example. In the parts which surround the umbo, the 

 radial walls of the palisade-cells are violet ; in the other parts of tho 



• Ber. Dcutsch. Bot. Gesell., v. (1887) pp. 423-30. 

 t See this Journal, 1887, p. 981. 



t Ber. Deutscli. Bot. Gesell., vi. (1888) pp. 33-6. § Ibiil., pp. 113-1. 



II Bot. Ztg., xlvi. (188S) pp. 209-20. t See this Journal, 186i7, p. I-IO. 



•' Ber. Deutsch. Bot. Gesell, vi. (1888) pp. 73-84 (2 figs.). 



