642 SUMMARY OF CURRENT RESEARCHES RELATING 10 



Physiology. 

 Nutrition and Growth- 



Permeability of the Sheath in Wheat-grains.* — II. Schroeder has 

 investigated the conditions of the permeability of the sheath of wheat- 

 drains, and now publishes an account of his experiments, which arc similar 

 to those of A. J. Brown with barley. The chief results are as follows : 

 Solutions of non-permeable substances like sodium chloride retard the 

 absorption of water in proportion to their concentration, but this retarda- 

 tion has no connexion with the cell-contents of the grain, since injured 

 grains do not show the retardation, the results being obtained only where 

 tin' sheath is uninjured. Peas, which have no selective, permeable mem- 

 brane, give the same results whether the sheath is injured or uninjured, 

 and are unaffected by change in the concentration of the solution. 

 Aqueous solutions of such substances as Na, NaCl, KG1, KN0 3 , MgS< f 4 , 

 etc., were unable to penetrate the sheath, while solutions of iodine, chloro- 

 form, acetone, and other organic compounds were readily absorbed. 

 Similar results were obtained with dead wheat-grains so long as the 

 sheath remained uninjured. The results appear to favour a physico- 

 chemical explanation, and the permeability is apparently connected with 

 a certain damp condition of the membrane which water alone can produce, 

 although in some cases alcohol was found to render non-permeable sub- 

 stances permeable. Under normal conditions of germination the perme- 

 ability is observed exclusively in the neighbourhood of the embryo, and 

 is in a longitudinal direction parallel to the surface of the grain. 



Action of Proteolytic Diastases.! — A. Fernbach and M. Schoen 

 publish a few observations upon the mechanism of the action of proteo- 

 lytic diastases based upon experiments made with papayotine, pancreatine, 

 and the proteolytic diastase of Tyrothrix tenuis, upon such albuminoids 

 as fibrin, casein, " lactocolle " (commercial casein), egg-albumin, and 

 gelatin. The experiments were made in simple acpieous solutions and in 

 solutions containing phosphates, e.g. phosphate of potassium, and it is 

 found that in all cases the activity of the diastase was considerably in- 

 fluenced and accelerated by the presence of the phosphates. The results 

 obtained are entirely in agreement with those previously obtained in 

 connexion with the diastases of malt. 



CRYPTOGAMS. 



Pteridophyta. 

 (By A. Gepp, M.A., F.L.S.) 



Morphology of Ophioglossum palmatum.J — F. 0. Bower publishes 

 some notes on the morphology of Ophioglossum (Cheiroglossct) palmatum, 

 the most outstanding type in a remarkable family. It grows on rotting 

 trunks. Fresh material having been obtained on the Blue Mountains of 



* Flora, cii. (1911) pp. 186-208 (4 figs.). 



t Comptes Rendus Acad. Sci. Paris, cliii. (1911) pp. 133-36. 



t Ann. of Bot., xxv. (1911) pp. 277-98 (3 pis.). 



