No. 1, NovEMBEB, 1921] PHYSIOLOGY 43 



262. Mellon, R. R., S. F. Aceee, P. M. Avery, and E. A. Slagle. The ionization 

 constants of glycerophosphoric acid and their use as buffers, especially in culture mediums. 

 Jour. Infect. Diseases 29: 1-G. 1921. — The precipitation of i^hosphates in culture media on 

 the alkaline side of neutrality can be prevented by the use of disodium glycerophosphate. 

 This salt being a solvent for calcium and magnesium salts can also be used in the washing of 

 agar, in the precipitation of casein, and for the study of the effect of calcium and magnesium 

 ions on the growth of various organisms. The ionization constants of the glycerophosphates 

 are about the same as those of the ordinary phosphates; the former can, therefore, be sub- 

 stituted as buffers. — Selman A. Waksman. 



263. Priestley, J. H. The mechanism of root pressure. New Phytol. 19: 189-200. 

 Fig. 1-2. 1920. — The attempt is made to interpret data presented by others bearing on the 



nechanism of root pressure. An osmotic gradient exists cell by coll from the root hair to 

 ohe xylem duct. The resultant entrance of water into the parenchyma within the endodermis 

 causes the development of a considerable hydrostatic pressure within the vascular cylinder, 

 since the endodermis is unable to expand because of the lignification of its radial walls. More- 

 over, it does not permit the passage of water except by osmosis through its protoplasts. The 

 assumption is made that increased permeability of the protoplasm of the parenchyma cells 

 adjoining ducts allows this hydrostatic pressure to force water and solutes into the ducts. — 

 Certain objections to the theory are considered. — I. F. Leivis. 



WATER RELATIONS 



264. MacDougal, D. T. Water deficit and the action of vitamines, amino-compounds 

 and salts on hydration. Amer. Jour. Bot. 8: 296-302. 1921. — The author suggests that plant 

 protoplasm is a colloidal mixture of 2 separate but interwoven aggregates, the proteins and 

 the pentosans, with soap films enclosing the more solid phase of the double meshwork. The 

 separate elements in this albumin-pentosan-soap structure differ in their capacity for hydra- 

 tion and in the conditions under which hydration may occur within them. The metals repre- 

 sented by the usual nutrient salts are found to increase the hydration capacity of the principal 

 components of biocolloids. The presence of a small amount of soap in a biocolloid increases 

 its hydration capacity, but this capacity is much lessened by even a very dilute acid. Yeast 

 vitamine (water-soluble B) in a solution slightly acid, increases the hydration in some living 

 and dead plant cell masses and lessens it in others; similar diverse action on biocolloids was 

 found. All of the substances tested which are known to facilitate growth in plants are found 

 to increase hydration capacity in some of the test objects. — E. W. Sinnott. 



265. Weiser, H. B., and E. E. Porter. Spontaneous evaporation. Jour. Phys. Chem. 

 24: 233-341. 1920. — Careful repetition of experiments by Babington (see Proc. Roy. Soc. 

 London 10: 132. 1859), which led the latter to conclude that some salts when dissolved in 

 water accelerate evaporation of the water, showed that these salts actually retard evaporation 

 and indicated that Babington's error was chiefly owing to an increase in surface produced by 

 a creeping of the solution, although failure to maintain constant conditions contributed 

 to the error. The authors found the use of a rotating table necessary to obtain concordant 

 results. — //. E. Pulling. 



PHOTOSYNTHESIS 



266. Anonymous. De koolzuirassimilatie in verband met de bemesting. [Carbon dioxide 

 assimilation in connection with manuring.] Cultura 33: 110-117. 1921. — A general outline 

 is given of the work of Blackman, Willstatter, Stoll, Klein, Reinau, Bornemann, and others. — 

 J. C. Th. Uphof. 



METABOLISM (GENERAL) 



267. Blackman, F, F. The biochemistry of carbohydrate production in the higher plants 

 from the point of view of systematic relationship. New Phytol. 20 : 2-9. 1921 . — Carbohydrate 

 production is analyzed into 3 strata: (1) The primary photo-reduction of carbonic acid 



