No. 1, August, 1921] GENETICS 39 



worms become in course of time (30 years or so) bivoltins with a tendency to univoltinism. 

 After bivoltinism is seemingly ostablishctl certain batches of cp^gs showed irregularity of 

 development producing both univoltins and bivoltins, the former being winter eggs, the latter 

 producing a second series of eggs, — summer eggs, — namely, accidental trivoltins. The latter 

 could be reared only by artificially raising the temperature. Hence under direct influence 

 of climate, number of generations can be reduced or multiplied as case may be. — Isabel 

 McCroflcen. 



244. Lehmann. [German rev. of: Rateson, W., and Ida Sutton. Double flowers 

 and sex linkage in Begonia. Jour. Genetics 8: 199-207. PI. 8. 1919 (see Bot. Absts. 3, 

 Entry 208).] Zeitschr. Bot. 13 : 2G2-263. 1921. 



245. Lehmann. [German rev. of: Heribekt-Nilsson, Nils. Zuwachsgeschwindig- 

 keit der Pollenschlauche und gestorte Mendelzahlen bei Oenothera Lamarckiana. (Rate of growth 

 in pollen-tubes and deranged Mendelian ratios in Oenothera Lamarckiana.) Hereditas 1: 

 A\-(Sl.lfig. 1920 (see Bot. Absts. G, Entry 16S9;7, Entry ICOI).] Zeitschr. Bot. 13: 99-102. 1921. 



246. Lehmann, E. [German rev. of: Ishikawa, M. Studies on the embryo sac and 

 fertilization in Oenothera. Ann. Bot. 32: 279-317. 1918 (see Bot. Absts. 1, Entries 482, 979, 

 980). 1 Zeitschr. Bot. 13 : 97-99. 1921. 



247. Lehmann. [German rev. of: Kanda, M. Field and laboratory studies of Verbena. 

 Bot. Gaz. 69: 54-71. 4 pL, 26 fig. 1920.] Zeitschr. Bot. 13: 2(32. 1921. 



248. Lehmann. [German rev. of: Stout, A. B. Intersexes in Plantago lanceolata, 

 Bot. Gaz. 68: 109-133. PI. 12-13. 1919 (see Bot. Absts. 3, Entry 1517).] Zeitschr. Bot. 13: 

 261. 1921. 



249. Linhart, George A. A simplified method for the statistical interpretation of experi- 

 mental data. Proc. Nation. Acad. Sci. 6: 6S2-6S4. 1920. — Data now in press are cited as show- 

 ing that all the types of frequency curves thus far published, excepting those having a zero 

 class, conform to the mathematical expression 



y -K-' 

 — = e 



2/c 



\ rrio/ 



when m denotes the numerical value of any measurement, vxo the value of the mean, e the base 

 of natural logarithms, y any frequency, and ?/o a frequency of the probability of a deviation zero. 

 From this equation, formulae for the mean, standard deviation, etc., are derived. — John 

 W. Gowen. 



250. Lotka, a. J. Evolution and irreversibility. Sci. Prog. [London] 14: 403-417. 

 1920. — Author's simamary follows: "It has been pointed out by biologists that organic evolu- 

 tion is an irreversible process. Physicists also have spoken of the second law of thermo- 

 dynamics broadly as the law of evolution. In inorganic physical systems irreversible proc- 

 esses are attended with a decrease in certain functions of the variables defining the state of 

 the system. In the case of organic systems we have not, in general, any such definite criteria 

 for irreversibility or for equilibrium. In the present contribution a broad formulation of 

 evolution, organic or otherwise, is presented in analytical form. From this it is shown that, 

 for certain cases, functions of the variables X and the parameters P defining the state of the 

 system, and of the coefficients a defining its characteristic properties, can be indicated, which 

 have the property, in the neighborhood of stable equilibrium, of diminishing in the (irreversi- 

 ble) process of the evolution of the system, and of assuming a minimum when stable equili'")- 

 rium is established. In these cases, therefore, it is possible to define in exact terms the 

 direction of evolution, whereas the descriptions ordinarily given of this direction (passage 

 from lower to higher, from simpler to more complex forms, etc.) are vague or inaccurate." — 

 R. E. Clausen. 



