222 EXPERIMENT STATION EECORD. [Vol.35 



with the different species, in some extending from June or July to March or 

 April, while with others growth may begin again after two or three weeks of 

 dormancy. 



An extensive bibliography is appended. 



The bearing of certain senile changes in plants on present theories of 

 senility, H. M. Benedict (Abs. in Science, n. ser., 43 {1916), No. 1104, p. 286).— 

 In a previous publication (E. S. R., 34, p. 222), the author described senile 

 degeneration in Yitis vulpina, and in the present paper he gives an account of 

 various theories regarding this phenomenon. He favors that advanced by 

 Kassowitz, that senility is due to an accumulation of inert catabolic products, 

 and he suggests that a more fundamental cause of senility may be found in the 

 colloidal constitution of protoplasm with its units in the form of molecular 

 complexes. 



The favorable influence of nitrogen salts on seeds sensitive to light, G. 

 Gassneu {Jahrb. Wiss. Dot. [Pringsheim], 55 {1915), No. 2, pp. 259-342; abs. 

 in Ztschr. Bat., 7 {1915), No. 9, p. 580).— Giving the detailed results of exten- 

 sive experimentation, the author states that the germination of seeds of 

 Ranunculus sceleratus, CEnothera biennis, and Chloris ciliata is favorably in- 

 fluenced by light. This effect in case of the first named required variations 

 of temperature, and these variations themselves favored germination. In case 

 of (E. biennis, light favored germination at both constant and varying tem- 

 peratures. Seeds of C. ciliata, when freed from chaff, were not so influenced 

 by temperature variations, and light acted favorably in this respect only at 

 temperatures of about 20° C. and upward. It is stated that germination is 

 favored not by nutritive media as such, but by salts containing nitrogen as 

 nitrites, nitrates, and ammoniates, the effects of which in this respect are 

 perceptible through a very wide range of concentrations. 



The author also discusses recent related experimentation as reported by 

 Ottenwalder (E. S. R., 33, p. 826). 



New instances of the promotion of germination, by nitrogen compounds, 

 of seeds sensitive to light, G. Gassner {Ber. Deut. Bat. Gescll., 33 {1915), No. 

 4, pp. 211-232). — Discussing the tabulated results of tests with plants in widely 

 separated families, the author emphasizes the fact that in these cases nitrogen 

 variously combined in the nutritive media was found to show the same favor- 

 able action as did light. Some doubtful or contradictory results are reported. 



Studies on light and temperature as related to the germination of seeds, 

 G. Gassnee {Ber. Deut. Bot. Gesell., 33 {1915), No. 4, pp. 203-217).— Giving 

 the results of studies by other investigators the author reports a continuation 

 of his own work (see above), using seeds of nine species of Onagraceise, one 

 of Hydrophyllacese, and two of Scrophulariaceae. 



It is stated that in the first group three different germination types may 

 be distinguished as regards their relation to light and temperatxire. The sec- 

 ond division is characterized by a low germinability optimum and by the 

 injurious action of high germination temperatures, the favoring action of 

 temperature change, and the unfavorable action of light at extreme germi- 

 nating temperatures. In the third gi-oup, the seeds require stronger light at 

 low temperatures. Temperature variations here also favor germination, espe- 

 cially when regular, giving the most marked results when the lower daily 

 temperatures were maintained for longer periods than were the higher tem- 

 pera,tures. 



Influence of temperature on the moisture intake of seeds, C. A. Shttll 

 (Abs. in Science, n. ser., 43 {1916), No. 1105, p. 329 ) .—According to the author, 

 a critical analysis of the data obtained as to the rate of moisture intake at 

 various temperatures by seeds possessing semipermeable coats, shows that the 



