628 EXPERIMENT STATION RECORD. 



The org-anization of the cell with respect to permeability, W. J. V. Oster- 

 HOUT {Science, n. ser., 38 (191S), No. 977, pp. 408, 409).— The author calls 

 attention to the fact that in studios on permeability more than one surface must 

 be considered. As an illustration of this, attention is called to a marine alga in 

 which the protoplasm surrounds a large cell vacuole. Experiments with this 

 showed that the outer surface of the protoplasm and the inner surface did not 

 act alike with respect to their permeability. 



A discussion of his experiments follows, and it is thought that the conception 

 of differential permeability may perhaps be extended to surfaces other than 

 those described. Since protoplasm is composed of a variety of structures and as 

 each of these has a surface, it is quite possible that many kinds of semipermeable 

 membranes may exist within a cell. 



An investig'ation into the structure and functions of the skin of the 

 pot *:o tuber, F. Stowabd {Jour. Nat. Hist, and Sci. Soc. West. Aust., 4 {1912). 

 pp. 57-79, pis. 4). — The author gives an account of studies on the morphology 

 and histology of the potato tuber, particularly with reference to the impermea- 

 bility of the skin of the tuber to salts and acids, the absorption of water by 

 tubers, and the effect of soaking tubers in brine and other salt solutions. 

 acids, etc. 



It was found that the skin of the cultivated tuber is protective against ex- 

 cessive loss of moisture and stored nutrient substances. The skin of the un- 

 damaged tuber is under ordinary circumstances impermeable to sjilts and acids 

 in solution. This impermeability, however, is not posses.sed by blight-infected 

 tubers. The skin of the tuber is held to be of considerable importance as a bar- 

 rier against fungus and bacterial invasion. 



Contributions to the study of nitrog'en nutrition in plants, I. Pouget and 

 D. Chouchak {Ann. Sci. Agron., 4. set:, 2 {1913), I, No. 4, pp. 2S1-302, figs. 5).— 

 Continuing former studies (E. S. R., 27. p. 826), the authors state as the result 

 of experiments in the nitrogen nutrition of millet that organic nitrogen was 

 directly absorbed. Nitric nitrogen was the most available form of nitrogen and 

 was absorbed almost or quite as rapidly as it is formed (differing herein from 

 ammonia, which may be found in soils with or without plants). In the begin- 

 ning of an experiment the influence of the nitrogen content of the soil water 

 was evident, but the increasing requirements of the plant in spring tend finally 

 to outrun the supply of available nitrogen, and the roots then play a part in the 

 solution of a new supply of nitrogen. 



Arsenic and manganese in leaves at different ages, F. Jadin and A. Asthuc 

 (Compt. Rend. Acad. 8ci. [Paris], 156 {1913), No. 26, pp. 2023, 202^ ) .—Refer- 

 ring to articles previously published (E. S. R.. 27, p 830; 28, p. 526; 29, p. 28). 

 the authors give the tabular results of analyses made at different stages of 

 growth on leaves of several plants. These are claimed to show that the relative 

 content of manganese or arsenic is greater in the older leaves, especially when 

 the fresh weight is taken, being often reversed if the ash weight is considered. 



Replacement of zinc by copper in the culture of Asperg-illus niger, C. Le- 

 piERRE {Bui. Soc. Chim. France. 4. ser., 13 {1913), No. 13, pp. 68 1-6S 4) .—The 

 author reports that in addition to cadmium, glucinium and uranium, previously 

 studied (E. S. R., 29. pp. 28, 422), later researches show that copper also is able 

 to replace zinc in Raulin's nutritive solution in cultures of A. niger, giving a 

 growth more rapid than in case of zinc or any of the others except uranium. 



The action of sulphuric acid on seeds, C. Bianchi {Staz. Sper. Agr. Ital., 

 45 {1912), No. 9, pp. 681-715).— As the result of studies on 30 species com- 

 prised in 16 genera and 7 families, the author concludes that treatment with 

 concentrated sulphuric acid shortens the period of germination in case of seeds 

 of the species studied, all of which are impermeable to water. The accelerating 



