ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 981 



Albumen in the Cell-wall.* — Herr F. Krasser, following up the observa- 

 tions of Wiesner f on the presence of albuminoids in the cell-wall, discusses 

 frthe value of the reagents at present used to determine the presence of 

 albuminoids. He finds that they fail in either not staining all albuminoid 

 substances, or they stain not only albuminoids, but also other substances 

 resulting from their decomposition. This is tbe case even with Millon's 

 reagent, which colours also tyrosin, hydroparacumaric acid, aud phenol. 

 The copper test, and sulphuric acid containing molybdic acid, are the least 

 reliable of any. A new test for albuminoids is proposed, viz. alloxan. 



As regards special tissues, in a very large number of plants examined, the 

 author was unable to determine with certainty the presence of albuminoids 

 in the cell-wall, either in the growing point of the stem or in the root. 

 None was found in the cell-walls of the root-cap, while those of the cambium, 

 pericambium, and phellogen were strongly coloured. In all the cases 

 examined — sixty-two in number — the cell-walls of the epidermis gave the 

 albuminoid reaction. This was also commonly the case with the elements 

 of the soft bast ; less often with those of the fundamental parenchyma and 

 pith. In ten cases a positive result was obtained with coUenchyma. With 

 the endosperm the result varied in different cases. 



As regards the source of the albuminoids found in the cell-wall, HeiT 

 Krasser comes to the conclusion, from the phenomena connected with its 

 development, that they are not the result of infiltration, but have been formed 

 in the course of its formation. 



Permeability to air of Cell-walls.j: — By the use of the air-pump 

 Herr E. Lietzmann has investigated the extent to which cell-walls, in various 

 conditions, can become permeated with atmospheric air, carrying out the 

 subject especially from a mathematical point of view. The objects specially 

 examined were cork, lamellaa from the tissue of the leaf of Peperomia magni- 

 folia, and lamellae of the wood of Pinus Laricio and P. sylvestris. 



With the pressures employed, cork was impermeable in the axial direction, 

 while the cuticle of Peperomia, the walls of the tracheids of Pinus, and 

 other cell- walls, were permeable. All cell-walls on which experiments were 

 made were more permeable to air in a saturated than in a dry condition. 

 The wood of P. Laricio was more permeable in the tangential than in the 

 radial direction. In P. sylvestris open tracheid-bundles were met with as 

 long as 22 centimetres, or perhaps longer. The living parietal utricle of 

 protoplasm is altogether impermeable, or permeable only to a very slight 

 degree. 



Swelling and Double Refraction of Cell-walls.§ — Herr S. Schwendener 

 discusses this subject from an experimental and mathematical point of view. 

 He agrees rather with the older view of Nageli than with that of v. Hohnel,|| 

 believing that the phenomenon in question is accompanied by shortening in 

 the direction of one axis as well as by lengthening in that of another, as is 

 shown by certain lines on the membranes. When the conditions of elasticity 

 in the direction of these lines are diflerent from those in a vertical direction, 

 torsion must result. The phenomena connected with swelling are described 

 in detail in the case of static-mechanical cells, of dynamic cells (bastlike 

 etereids with transverse cleft-shaped pores), of cork-cells with cellulose- 

 thickenings, and of the elongated cells of Caulerpa. 



* SB. K. Akad. Wiss. Wien, xciv. (1887) pp. 118-55. 



t See this Journal, 1886, p. 818. 



J Flora, Ixx. (1887) pp. 339-86 (1 pi.). 



§ SB. K. Preuss. Akad. Wiss. Berlin, xxxiv. (1887) pp. 659-702 (4 figs.). 



II See this Journal, 1883, p. 90. 



