No. 2, December, 1921] PHYSIOLOGY 117 



authors regard it as a statement of a general biological law. A large series of determina- 

 tions in the various non-halophytic habitats of the north shore of Long Island" indicate 

 "that while the concentration of ionized electrolytes is lower in ligneous than in herbaceous 

 forms, the reverse is true for total solutes." This conclusion, it is stated, cannot be adjudged 

 general unless confirmed by investigations now in progress. — //. E. Pulling. 



746. Hill, A. V. The application of physical methods to physiology. Sci. Prog. [London] 

 16: 79-S9. 1921. — A plea is made for the adoption of physical methods of investigating 

 the physical manifestations of life. The progress made in the past few years in the physical 

 and chemical sciences is discussed, and it is pointed out how this has been accompanied by 

 additions to our knowledge of the physiology of living organisms. — J. L. Weimer. 



747. MacDougal, D. T. The action of bases and salts on biocoUoids and cell masses. 

 Proc. Amer. Phil. Soc. 60: 15-30. 1921. — The strong metalic bases used as hydroxides or as 

 chlorides in concentrations of 0.01 M restrict the hydration of agar according to their relative 

 positions in the electromotive series. The series runs Ca, K, Na, the greatest retardation 

 being effected by calcium. Reversed effects on the hydration of agar were shown by the 

 hydroxides at 0.001 M, and also by the chlorides of calcium, magnesium, potassium, and sodium 

 at 0.001 M. Purified agar shows more swelling in HCl at Ph 4.2 than in water, and shows 

 exaggerated swellings in a series of acid, salt, and hydroxide solutions of Ppi 4.2-11. The 

 maximum swelling of a gelatin-agar (3 parts gelatin and 2 parts agar) plate was found at 

 0.01 M for HCl, at 0.001 M for KCl, and at 0.0001 M for CaCla- Different ecological types of 

 roots of maize show different hydration reactions to the solutions used. Roots of strawberry 

 and of orange seedlings show differing hydration reactions when grown in saline soils, in 

 sand, or in acid solutions. Effects as of balanced solutions are defined in the relation of 

 certain salts to the hydration of agar, and some suggestions of similar action are noted in the 

 biocolloids employed. — Wanda Weniger. 



748. ScHADE, H. Die KoUoide als Trager der Lebenserscheinungen. [Colloids as carriers 

 of life.] Naturwissenschaf ten 9 : 89-92. 1921. 



749. Sprecher, A. Recherches cryoscopiques sur des sues vegetaux. [Cryoscopic in- 

 vestigations of plant juices.] Rev. Gen. Bot. 33: 11-33. PL 35. 1921.— The juices of varie- 

 gated leaves, both yellow and dark red, showed less osmotic pressure than green varieties. 

 Variegated nasturtium showed a large proportion of salts in the sap. Those with dark red 

 foliage possessed the largest amount of dry residue in relation to the osmotic pressure, and the 

 yellow and variegated foliage the least. The osmotic pressure of Tropaeolum varied during 

 the day, being lowest in the morning and highest in the afternoon. Removal of the flower 

 buds increased the amount of dry residue as well as the osmotic pressure, but this increase was 

 less than in plants which had bloomed. The osmotic pressure was greatest in the sap of the 

 leaf blades of Tropaeolum, less in the branches, and least in the petioles. In Helianthus the 

 petioles showed the highest osmotic pressure, and then, in order, the leaf blade, the branches, 

 the pith, and the petals. In the case of the brown variety of Coleus VershaffelH and a yellow 

 variety the difference in osmotic pressure was slight. The osmotic pressure of plants is more 

 rapidly changed by the changes in the relative humidity of the environment than by tempera- 

 ture or light. Species with leaves characterized by large cells exhibit osmotic pressures 

 equal to that of species with small cells. — /. C. Oilman. 



750. Waller, A. D., Mrs. A. D.Waller, F. O'B. Ellison, and T. B.F.\rmer. Electro- 

 motive phenomena in plants. Rept. British Assoc. Adv. Sci. 1920: 266. Pl.l. 1920.— The 

 following conclusions are drawn from experiments carried out upon Iru germanica: "1. The 

 basal zone of the Iris leaf, in which alone active growth is in progress, is electrically active 

 (zincative) in relation to parts where active growth has ceased. II. The zone of active growth 

 is aroused to greater physiological activity (that is, is more zincable) than are parts in which 

 growth is not proceeding." — C. L. Wilson. 



