28 EXPERIMENT STATION EECORD. 



cytologic:!] and morphological characters and inheritance, particularly as noted 

 in species of CEnothera and their mutants. 



Growth and variation in maize, R. Peael and F. M. Surface (Proc. Nat. 

 Acad. Sci., 1 {1915), No. 4, pp. 222-226, fig. 1; als. in Maine 8ta. Bui. 234 

 {1914), pp. 290, 291).— The investigation reported in this paper is an attempt 

 to analyze the normal variation of maize from the standpoint of its develop- 

 ment. The authors tried, by studying the growth of the individual, to analyze 

 the adult variation curve into its component elements as a beginning at an 

 understanding of the developmental physiology of the genes concerned in the 

 production of the characters studied. Measurements were made twice a week 

 of the height of each individual of three series of plants of a A-ariety of sweet 

 corn. 



The evidence indicates that the observed differences in the manner of growth 

 of individual plants and groups of plants can not be explained as the effect of 

 external environmental factors, but are rather to be looked upon as the effect 

 of internal factors. The distribution of the average relative size of individual 

 plants is such as to suggest the random distribution of these factors among 

 the plants. The simplest method of explaining these facts is believed to be to 

 regard the differences in the manner of growth as due to independent Mendelian 

 factors which are distributed at random in any population of open fertilized 

 maize plants. By assuming the presence of two independent growth factors 

 and weighing each with the proper value, the authors consider it possible to 

 obtain a theoretical distribution which agrees very closely with the observed 

 distribution. The interpretation of the growth of these plants by Mendelian 

 factors is said to be strongly supported by the distribution of the standard 

 deviation of the plants with different relative sizes. 



The causes of growth in plants, III, G. A. Borowikow {Eolloid ZtscJir., 15 

 (1914), No. 1, pp. 27-30).— Having noted (E. S. R., 29, p. 420) that the hydra- 

 tion of plasma colloids appears to be one of the most important factors in plant 

 growth, at least in case of Eelianthus annuus, and that an exception to this 

 rule may be observed to result from the presence of the respiratory product 

 carbon dioxid in the nutritive solution, the author has carried out further 

 investigations which are here briefly discussed. 



It was found that concentration of the cell sap and rapidity of growth bear 

 an inverse rather than a direct relation to each other, slight alterations in 

 the one often corresponding to great changes in the other, the possible bearings 

 of this fact being discussed. It is thought that the periods of growth through 

 which each cell passes may be related to stages in the rapidity of hydration 

 of the cell colloids. 



Purther studies on the colloidal and physical chemistry of the cell, W. 

 RriiLAND {Jahrh. Wiss. Bot. [Pringsheim], 54 {1914), No. 3, pp. 391-447).— 

 The author has continued work previously noted (E. S. R., 30, p. 28), detailing 

 results and inferences from a study of carbohydrates, alkaloids, glucosids, and 

 acids, also those from a study of the physicochemical properties of the cell in 

 general and of the cell as an ultra-filter in particular. It is stated that the 

 function of an ultra-filter is exercised by the plasma membrane and not by 

 the cell wall. 



The influence of ultraviolet rays on chlorophyll-containing cells, J. Stok- 

 LASA {Ztschr. Pflanzenkrank., 24 {1914), No. 4, pp. 193-204).— In the course of 

 numerous experiments here reported, dealing with a number of plants, it ap- 

 pears that the briefer exposures (two hours) to ultraviolet rays (of wave lengths 

 300 to 500mm) generally cause rapid development of chlorophyll in etiolated 

 leaves, while longer exposures either produce results not much greater than 



