442 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including: Cell-Contents. 



Permeability of Protoplasm. * — Van Rysselberghe, working in 

 Pfeffer's laboratory, bas made observations on the influence of tempera- 

 ture on the permeability of living protoplasm ; a field of work almost 

 untouched except for the observations of Krabbe in 1896. The chief 

 methods of observation were the study of the contraction and expansion of 

 living elder pith under various conditions, and the direct observation 

 under the microscope of cells of the epidermis of Trade scantia. The 

 author shows, as Krabbe found, that the permeability increases with the 

 rise of temperature (at 30° C. the protoplasm being eight times more 

 permeable than at 0° C.) ; the increase of permeability is different from 

 that found in a precipitated membrane of copper ferrocyanide, but it is 

 shown that this is no reason for believing with Krabbe, that this change 

 is due to a vital action of the protoplasm. Contrary to the general 

 opinion the permeability was found to be only reduced, not in complete 

 abeyance, at 0° C, and this applied not only to the passage of water but 

 also to that of dissolved substances. The passage of water was found 

 to take place under very reduced osmotic pressures (probably at 0-0023 

 of an atmosphere) so that probably there is no minimum force of filtra- 

 tion, as Krabbe believed, below which no passage of water takes place. 

 It was further found that a cell, the cell-sap of which is isotonic with a 

 certain solution at one temperature, Temains isotonic with the same 

 solution at all temperatures, provided that changes in the cell-sap have 

 not had time to take place by adaptation. It is thus clear that the 

 changes in the osmotic pressure in the cell is the same as that in a 

 solution, namely, -^X^ for every degree of temperature. 



Aleurone-Grains in Oily Seeds.f — Bille Gram has examined tbe 

 character and reactions of all the elements of the grain — tegument, 

 fundamental mass, globoid, crystal, and crystalloid. He confirms the 

 refractory character of the coat, manifested in its insolubility in 5 p.c. 

 solution of caustic potash. The fundamental mass consists mainly of 

 albuminoids, which in different grains show different degrees of solu- 

 bility in dilute caustic potash ; various other substances are present. 

 He finds in the globoid not only the acid phosphates of calcium and 

 magnesium signalised by Pfeffer but also succinic acid. From their 

 behaviour with solvents globoids would appear to have, generally 



* Recueil de l'lnetitut Botanique University de Bruxelles, v. (1902) pp. 209-49 



(6 pis.). 



+ Mem. Acad. Roy. Sci. &c. Danemark, se'r. 6 (Section d. Sciences) ix. (1901) 



pp. 303-36 (4 pis.). 



