296 PHYSIOLOGY [BoT. Absts., Vol. X, 



DIFFUSION, PERMEABILITY 



1921. Eaton, S. V. Osmotic pressure in the potato. [Rev. of: Lutman, B. F. Osmotic 

 pressures in the potato plant at various stages of growth. Amer. Jour. Bot. 6: 181-202. 2 fig. 

 1919 (see Bot. Absts. 3, Entry 800).] Bot. Gaz. 69: 272. 1920. 



1922. Eggerth, a. H. The preparation and standardization of collodion membranes. 

 Jour, Biol. Chem. 48: 203-221. 1921. — A simple method of preparing a graded series of col- 

 lodion membranes of wide range of permeability is presented. — G. B. Rigg. 



1923. Waller, A. D. On the contractility of amputated parts of plants. Jour. Physiol. 

 54: Iv-lvii. 1920. — Elongation as a result of growth and as a result of turgor changes differs 

 in that the former is irreversible and the latter reversible. At magnifications of 1000 con- 

 tractions which are visible are not "necessarily due to vegetable contractility analogous with 

 the contractility of animal muscles," but are due to turgor changes. Tetanisation of plant 

 parts may be similar to a corresponding phenomenon in non-living materials, such as a fiddle 

 string, and is not to be taken as evidence of "physiological contractility nor of a physiological 

 modification of growth." — Ernest Shaw Reynolds. 



1924. Wright, A. E. On "intertraction" between albvmiinous substances and saline 

 solutions. Proc. Roy. Soc. London B, 92: 118-124. 1921. — Layers of egg albumen or serum 

 separating pure water (above) from hypertonic salt solution (below) interfuse with the latter 

 only. Finger-like processes extend from the albumen into the salt solution and vice versa. 

 Aqueous bacterial suspensions penetrate very short distances into hypertonic salt solution 

 while serum suspensions migrate rapidly throughout. — Paul B. Sears. 



MINERAL NUTRIENTS 



1925. Canals, E. Du role physiologique du magnesimn chez les vegetaux. [The physio- 

 logical role of magnesivmi in plants.] Theses. (S6rie A. No. 859, No. d'ordre 1G59.) 133 p., 

 4 pi. Roum^gous and Dehan: Montpellier, 1920. — The author examined the methods of 

 quantitative determination of magnesium and calcium in plants and found that for accurate 

 work great care must be exercised not to vary the methods of precipitating the 2 substances. 

 Calcium was obtained in the form of calcium oxalate and magnesium in the form of magnesium 

 pyrophosphate. — With the exception of the grasses, analyses of different types of plants 

 showed a higher percentage of magnesium in the stems than in the roots. Hydrophytes as a 

 group gave higher percentages of magnesium than the xerophytes. Among the ferns the 

 xerophytic types gave a higher percentage than the hydrophytes. — Using Detmer's solution 

 in which the magnesium sulphate content was varied from 0-1000 mgr. per 1., the author 

 found that roots of peas and corn reached tlieir maximum growth in a solution containing 

 500 mgr. per 1.; for stems the optimiun was 100 mgr. Aspergillus niger in Robert's solution 

 gave a maximum growth with 500 mgr. of magnesimn sulphate per 1, No growth was ob- 

 tained in magnesium-free solutions. — Magnesium is toxic only in excessive quantities. — 

 Ferd. S. Wolpert. 



1926. Hart, E. B., H. Steenbock, and C. A. Hoppert. Dietary factors influencing 

 calcium assimilation. I. The comparative influence of green and dried plant tissue, cabbage, 

 orange juice, and cod-liver oil on calcixmi assimilation. Jour. Biol. Chem. 48: 33-50. 1921. — 

 Limited data indicate that the same factor (vitamin) affecting calcium assimilation and 

 resident in green oats and grasses is present in cod-liver oil. — G. B. Rigg. 



1927. Peters, R. A. The effect of substituting uranium for potassium in growth media. 

 Jour. Physiol. 54: li-lii. 1920. — In quartz tube cultures uranium could not be substituted 

 for potassium and give 3—4 sub-cultures of Colpidiurn. When added to a potassium culture, 

 uraniiun stimulated growth. Radio activity of potassium is not its sole use in cultures — if 

 it has such a function. — Ernest Shaio Reynolds. 



