1918] AGRICULTUBAL BOTANY. 25 



normal, six-normal). The embryonal halves of desiccated hulled Oryza were 

 capable of germination after 24 hours' steeping in commercial absolute ethyl 

 alcohol, ethyl ether, ethyl alcoholic (commercial absolute) solution of resorcin, 

 acetic acid, hydroquinone, and naphthalene, while the entire air-dried hulled 

 grains were killed by similar treatments. Twenty-four hours' steeping in the 

 aqueous solution of phenol, resorcin, a-naphthol, hydroquinone, acetic acid, and 

 mercuric chlorid was fatal to both desiccated and air-dried Oryza (hulled) and 

 Zea, whereas the corresponding alcoholic (commercial absolute) or ether solu- 

 tions were harmful only to a considerable extent. 



Hulled grain of Oryza can be germinated at an extremely low oxygen pres- 

 sure, but under such conditions the development of the radicle is totally pro- 

 hibited. A supply of oxygen initiates the development of the radicle in seed- 

 lings thus germinated. No appreciable stimulation was observed in the germina- 

 tion of Oryza from the influence of H and OH ions. 



The germinability of Oryza, Zea, and Fagopyrum was practically unaffected 

 by a few hours' exposure to the extremely low temperatures of liquid air, but 

 two hours' exposure at 97 to 98° C. completely destroyed the vitality of Zea, 

 while that of Oryza, especially of the desiccated seed, was only slightly af- 

 fected. 



An extensive bibliography is appended. 



Permeability of certain plant membranes to water, F. E. Denny {Bot. 

 Gaz., 63 (1917), No. 5, pp. S73-397, figs. 2).— In the course of a study involving 

 quantitative measurements of the permeability of certain nonliving plant mem- 

 branes under controlled conditions and employing apparatus and methods for 

 which delicacy, exactness, and constancy of osmotic pressure are claimed, the 

 author found that in the seed coat of Arachis hypogcea the temperature coeffi- 

 cient of permeability to water is lower than that required by the van't HofC law 

 but higher than the diffusion coefficient. No evidence appeared that either 

 chemical or physical processes are exclusively involved in the passage of water 

 through the membrane. The temperature coefficient showed higher values at 

 lower temperatures and lower values at higher temperatures, this being in 

 agreement with the behavior of temperature coefficients in other processes. 

 CJomparison is made with the results obtained in other experiments by several 

 other investigators named. 



No hysteresis or after effect of a previous temperature was observed. Water 

 passed more rapidly from the external toward the internal portion of the seed 

 than in the opposite direction in the case of both peanut and almond. With 

 distilled water on one side of the membrane, a sodium chlorid (but not a 

 sugar) solution produced a rate of movement proportional to the osmotic pres- 

 sure. Complex relations were observed when solutions of varying concentra- 

 tions were opposed, and in general equal osmotic differences did not necessarily 

 produce equal rates of movement, nor was any mathematical relation observed 

 between the concentrations on opposite sides and water movement. The bear- 

 ing of these facts is discussed. Ck)nsiderable differences appeared in a com- 

 parison of the permeability of several plant membranes made under similar 

 conditions. 



Does the temperature coefficient of permeability indicate that it is chemi- 

 cal in nature? W. J. V. Ostebhout (Boi. Gas;., 63 {1911), No. 4, pp. 317- 

 320). — The author, referring to the claim made by Stiles and Jorgensen (E. S. 

 R., 35, p. 224) that the absorption of hydrogen ions by tissues of the potato 

 has the temperature coefficient of a chemical reaction, cites experiments with 

 disks of Lamlnaria packed In a roll through which a current was passed in 

 which the temperature coefficient obtained was 1.33 while living, but dropped 

 to 1.26, practically that of sea water, after the tissue had been killed. 



