1919] AGRICU'LTURAL BOTANY. 631 



tiiiued in experiments conducted in quartz and soil. Tlie tliree series tliat 

 tiave been made are believed to liave established the physiological balance in 

 soil cultures. 



Porous clay cones for the auto-irrigation of potted plants, B. E. Livingston 

 (Plant World, 21 (1918), No. S, pp. 202-20S, fig. i).— An account is given of the 

 construction, operation, and advantages of a plan for auto-irrigation in the 

 study of plants. 



A comparison of permeability in plant and animal cells, W. J. V. Ostek- 

 HOUT (Jour. Gen. Physiol., 1 (1919), No. If, pp. 409-^13) .—Ttiska of Laminaria 

 were studied in connection with comparable pieces of skin taken from the frog 

 (Rana pipiens). The quantitative results showed a striking agreement between 

 the two kinds of tissues as regards certain important aspects of permeability, 

 antagonism, injury, recovery, and death. 



Decrease of permeability and antag'onistic effects caused by bile salts, 

 W. J. V. OsTEEHOUT (Jour. Gen. Physiol, 1 (1919), No. J,, pp. 405-^^08, flys. 2).— 

 As a result of experiments made by determining the electrical conductivity of 

 Laminaria in solutions to which sodium taurocholate had been added, the author 

 states that this salt decreases permeability and antagonizes sodium chlorid. 

 This fact confirms the hypothesis that antagonistic relations can be predicted 

 from studies on permeability. 



Antag'onism between alkaloids and salts in relation to permeability, W. J. 

 V. OsTERHOUT (Jour. Gen. Physiol, 1 (1919), No. 5, j)p. 515-519, flys. 3).— In 

 order to compare antagonism between alkaloids and salts with that between 

 salts and other salts, the author carried out experiments on Laminaria with 

 nicotin, caffein, and cevadin added in varying amounts to sodium chlorid at 

 0.52 M, 



It appears that solutions which have opposite effects on permeability antag- 

 onize each other in case of alkaloids as well as in that of salts. It also appears 

 from this work that certain alkaloids which decrease permeability are able to 

 antagonize sodium chlorid, in this respect resembling salts which decrease 

 permeability. 



The effect of ions of sodium chlorid and calcium chlorid upon the electri- 

 cal conductivity of certain colloidal mixtures, N. B. Green (Plant World, 21 

 (1918), No. 12, pp. 303-316, flys. 7). — Experiments here outlined were suggested 

 by the discovery of Osterhout (E. S. R., 26, p. 823) that the permeability of 

 plant tissues to various ions can be determined by measuring the resistance 

 offered by such tissues to an electric current. It was found in the present work 

 that when one salt is allowed to penetrate the colloid for a time, and then a 

 second salt substituted, the rate of penetration by the ions of the latter seems 

 to be unaffected by the presence of the former. The mixed solution of sodium 

 chlorid and calcium chlorid showed a fall of resistance similar to that of either 

 of the constituents alone, the curve approaching more nearly that of the pre- 

 dominant salt. Ions of these two substances do not antagonize one another 

 as regards penetration of certain colloidal gels, notably gelatin or mixtures 

 of gelatin, agar, and whole wheat flour. 



Determinations of electrical resistance in solutions of gelatin to which salts 

 had been added in varying concentrations showed that the electrical resistance 

 of the gelatin varies directly with the precipitability, which is greatest at the 

 isoelectric point, that is, where the uuadsorbed + and — ions of the added 

 salts balance one anotlier. 



The water requirement of plants as influenced by environment, L, J. Briggs 

 and H. L. Shantz (Proc. 2. Pan Amer. Sci. Cong., 1915-16, vol 3, pp. 95-107, 

 pis. 2, flgs. 4). — From experiments with grain and otlier plants, described as 



