ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
53 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
Cl) Cell- structure and. Protoplasm. 
Behaviour of Vegetable Cells to a very dilute Alkaline Silver- 
Solution.* * * § — Returning to this subject, Herren 0. Loew and T. Bokorny 
give the following as the general result of a number of fresh experi- 
ments, chiefly on Spirogyra. 
The reduction of an extremely dilute alkaline silver-solution by 
vegetable cells does not depend on the presence of a reducing substance 
soluble in water, but on a reaction of the albumen of living cells. The 
failure of this reduction in dead cells, or in those killed by heat, acids, 
&c., is not the result of the exosmose of a reducing substance, but of a 
chemical change in the albumen. The albumen of living cells coagu- 
lates from the fluid parts by the action of many bases, in the form of 
globules, for which the authors propose the name proteosomes ; they 
have an energetic reducing action on very dilute alkaline silver- 
solutions ; and it is on their formation that the direct reaction of living 
cells with alkaline silver-solutions depends. Proteosomes cannot be 
produced in dead cells. 
A silver-solution free from ammonia can be obtained by adding 
to a litre of distilled water 0*01 gr. of silver nitrate, and 5-10 ccm. of 
saturated lime-water. This reagent gives essentially the same results 
with algae free from tannin and with those which contain it. 
Doubly-refractive Power of Vegetable Objects. j* — Prof. S. Schwen- 
dener replies to the objections of Ebner and C. Muller against his 
previously published views on this subject. The experiments of the 
first-named observer were, he states, made on fluids rather than on 
solids. 
(2) Otlier Cell-contents (including: Secretions). 
Green Colouring-matter in Buried Leaves.^ — Mr. W. Thomson 
describes a bed of leaves still retaining a distinct green colour, found 
at a depth of 21 feet below the surface when digging for the Manchester 
ship-canal, which must have lain in the same position certainly for some 
centuries. 
Dr. E. Schunck § has determined this colouring-matter to be modified 
chlorophyll resulting from the action of acids on true chlorophyll. 
Localization of Tannin.H — Herr M. Biisgen states that in some 
plants tannin is present even in the seed, although in most it is not found 
* Bot. Centralbl., xxxix. (1889) pp. 369-73; xl. (1889) pp. 161-4, 193-7. Cf. 
this Journal, 1888, p. 244. 
t SB. K. Breuss. Akad. Wiss., xviii. (1889) pp. 233-44. Cf. this Journal, 1887, 
p. 981. 
X Mem. and Proc. Manchester Lit. and Phil. Soc., ii. (1889) pp, 216-9. 
§ T. c., pp. 231-3 (1 fig.). 
11 Jenaisch. Zeitschr. Naturw., xvii. (1889). See Bot. Centralbl,, xxxix. (1889) 
p. 318. 
