19171 AGRICULTITRAL BOTANY. 725 



that have no counterpart in the /3 gametes. Sperms of the form typica being 

 P gametes, mutations appear whenever a mutated a gamete is fertilized. They 

 do not appear as a result of segregation. 



A new type of non-Mendelian variation in plants, S. Ikeno (Bot. Mag. 

 [Tohyo], 29 (1915), No. 346, pp. 216-221, fig. 1; abs. in Arm. Bot. [Rome], 14 

 {1916), No. 2, p. 109). — The author reports having found in heredity tests with 

 Capsicum annuum that variegation was transmitted from either parent or 

 both. The nimabers produced, however, were smaller when variegated plants 

 were crossed with green than with variegated ones, the Mendelian formula 

 not applying in these results. 



The relation between evaporation and plant succession in a given area, 

 F. C. Gates (4r7ier. Jour. Bot., 4 (1917), No. S, pp. 161-178, figs. 9).— Experi- 

 mentation was carried on during the summers of 1915 and 1916 with 42 stand- 

 ard atmometers, employing the usual methods. Owing to the smallness of the 

 area covered the influence of edaphic factors was not obscured by the operation 

 of broad climatic factors. 



Invasion, the initial stage of succession, must take place, it is claimed, under 

 the conditions already existing. A change of conditions coincident with me- 

 sophytic succession may result in a decrease in the rate of evaporation in the 

 ground or chamaephytic layer. Evaporation differences are due to the size 

 and density of the surrounding vegetation. While a decrease in the evaporation 

 is not a prerequisite to succession, a change in the dominant species of an area 

 is fundamental thereto. The change in evaporation is a result and not a cause 

 of succession. While certain species develop imder existing conditions to bring 

 about succession, species of narrower physiological limitations can not develop 

 until the conditions come within their range. These are secondary species, un- 

 able to cause succession, the occurrence of whicli requires the arrival and devel- 

 opment of the dominant species of a higher genetic association. 



Adaptations of vegetation to climate, J. Massabt (Ann. Geogr., 26 (1917), 

 No. 140, pp. 94-105, pi. 1). — This is an account of the conditions and behavior 

 observed in a study of vegetation in portions of France which are subject to 

 somewhat exceptional climatic and seasonal influences and changes. It is stated 

 that each function in the economy of the plant, as germination, growth, rosette 

 production, etc., has its optimum temperatures lying within limits which are 

 more or less narrow according to species, and that in order to understand the 

 adaptation of a plant to heat (as an example of influential climatic elements) it 

 is necessary to study the plant in all the successive phases of its life and in re- 

 lation to the various exigencies to which it is normally subjected. 



Temperature and life duration of seeds, J. F. Geoves (Bot. Gaz., 63 (1917), 

 No. 3, pp. 169-189, figs. 5). — Employing Turkey red wheat, the author has sought 

 to determine to what extent a study of the life duration of seeds at high tem- 

 peratures (50 to 100° C.) will explain the process of degeneration of air-dried 

 seeds at ordinary storage temperatures. The life durations of wheat with 9, 

 12, and 17.5 per cent moisture are given for various temperatures, and the de- 

 gree of application at high temperatures of the Lepeschkin formula (E. S. R., 

 29, p. 27) is indicated. 



No definite trend appears In the value of the temperature coefficient Qio (sym- 

 bolizing the Van't Hoff law), and its range is confined to rather narrow limits. 

 It is held that there is no justification for placing much emphasis on predicted 

 longevities at low temperatures. 



This work indicates some of the possibilities of throwing light on the nature 

 of the processes of the loss of viability in seeds in storage conditions, and it 

 makes possible a quantitative statement of the significance of storage condl- 



