ZOOLOGY AND BOTANY, MIOKOSCOPY, ETC. 67 



hand, the firmness is greatest in the direction of the rows of micella 

 and of the pores. 



3. The cause of the torsion of the legumes of Orobus and 

 Caragana resides in the layer of resin, and is brought about in it by 

 unequal contraction in the transverse direction, which is indicated 

 by anatomical differences. The outer epidermis (and its anatomical 

 strengthening in Caragana) acts only by increasing the strength of 

 the mechanism, the vascular bundles of the margin detracting from 

 its efficiency. 



4. The torsion of the awns of Geranium is caused by unequal con- 

 traction of the cells in the longitudinal direction, these cells manifesting 

 also diiferences in the form and direction of their pores. In the awns 

 of Pelargonium the outer strongly developed epidermis effects the 

 torsion by strong curvature, the direction of the torsion being ren- 

 dered spiral by the tendency to torsion of the inner cells. 



5. The violent expulsion of the seeds of Oxalis is not caused by 

 turgidity, but by the energetic swelling of the cell-walls of the trans- 

 parent outer layer. 



Chemical Difference between dead and living Protoplasm. — 

 The view maintained by O. Loew and T. Bokorny,* that living cells 

 are chemically diiferent from dead ones, in that living protoplasm 

 shows an aldehyde nature by its power of reducing extremely dilute 

 alkaline silver solutions, while dead protoplasm does not, has been 

 the subject of an interesting discussion at the Berlin Chemical Society, 

 when Herr Eeinke denied the chemical difference, and insisted that 

 at least a part of the reaction is due to a volatile substance of alde- 

 hyde nature which is very frequent in green cells, and which he is 

 disposed to regard as formic aldehyde, the first product of assimilation 

 of carbonic acid in the plant. 



His opponents urged that they had carefully examined the dis- 

 tillation products of various species of AlgEe and of germs without 

 chlorophyll, but had quite failed to find any silver-reducing sub- 

 stance. Thinking, further, that they might have been misled by the 

 action of sugar or tannin, they convinced themselves that cells reduce 

 which have neither of these substances, and a living cell will easily 

 reduce a very dilute silver solution which sugar and tannin fail to 

 reduce. The intimate relation between silver-reducing power and 

 life (in their opinion) is shown clearly by the fact that in whichever 

 of many different ways cells of Algae were killed, the reaction in 

 question ceased with their death, and precisely at the degree of 

 temperature at which life is extinguished. This is generally the ease 

 in killing by poison ; strychnine alone being an exception, which is 

 explained by the existence of a combination of the alkaloid with 

 molecules of the active albumen. 



Energy of Growth of the Apical Cell and of the youngest 

 Segments.! — M. Westermaier commences a dissertation on this subject 

 with an historical sketch. Naegeli and Schleiden attributed the causes 



* See this Journal, i. (1881) p. 906. 



t Pringsheim's Jahrb. wies. Bot., xii. (1881) pp. 439-72 (1 pi.). 



F 2 



