No. 1, November, 1921] GENETICS 23 



120. Riddle, O. Differential survival of male and female dove embryos in increased and 

 decreased pressures of oxygen. A test of the metabolic theory of sex. Proc. Soc. Exp. Biol. 

 Med. 18: 8S-91. 1920. — The attempt is made to measure the relative metabolic rates of dove 

 embryos of different sex. Because of difficulties in doing this directly, the experiments were 

 devised to test the differential survival of the sexes when the eggs during incubation were 

 subjected to increased and decreased oxygen pressures and to low temperature for varying 

 periods. It is argued that if male embryos have a higher metabolic rate than females they 

 should succumb more readily to diminished oxygen pressure and vice versa, and the low tem- 

 perature should by the same reasoning be more harmful to the males. Data are given which 

 are interpreted as supporting this conclusion. — L. J. Cole. 



121. Rowan, W., E. Wolff, the late P. L. Sulman, K. Pearson, E. Isaacs, E. M. 

 Elderton, and M. Tildesley. On the nest and eggs of the common tern (S. fiuviatilis). 

 A cooperative study. Biometrika 12 : 308-354. 6 pi. 1919. — The authors report the continua- 

 tion in 1914 of the study of a tern colony made in 1913. The following characters were re- 

 corded: (1) Length, (2) breadth, (3) longitudinal girth, (4) transverse girth, (5) tone or ground 

 color, and (G) mottling, of eggs ; and (7) type of nest, whether a simple depression in the ground 

 or constructed of nesting materials. From a statistical treatment of these data more or less 

 definite conclusions are reached. Some of these are as follows: As in 1913, broader eggs tend 

 to have less mottling, attributed to possible pressure on the surface of the egg as it passes 

 through the oviduct, thereby influencing the amount of pigment deposited. The eggs of 

 1914 are significantly larger and less variable, possibly correlated with a better food supply. 

 Correlations believed significant were obtained between relatively longer eggs (those with 

 greater ovality) and more elaborated nests. While correlation of nest type with ground color 

 (brown or green) of egg was not significant, eggs with finer blotches seemed to be associated 

 more frequently with the more elaborate nests; moreover "denser browns and lighter greens 

 are somewhat more usual when the nest is a mere hole in the shingle, and lighter brow^n and 

 darker green eggs are associated with more elaborately constructed nests." — The proportion 

 of green to brown eggs in a clutch increases with the size of the clutch. Various explanations 

 are suggested and tested statistically. Several other correlations are considered and there 

 is some discussion of the physiological and evolutionary bearings of the results. — L. J. Cole. 



V22. Salisbttrt, E. J. [Rev. of: Reinheimer, H. Symbiosis. A socio-physiological 

 study of evolution, xii + 295 p. Headley Brothers: London, 1920.] Sci. Prog. [London] 

 IS: 671. 1921. 



123. Schrader, Franz. The chromosomes of Pseudococcus nipae. Biol. Bull. 40: 

 259-270. 2 pi. 1921. — The diploid number of chromosomes in both the male and the female 

 of Pseudococcus nipae is 10. In the female, 5 tetrads are formed; these are normal in appear- 

 ance. In the growth period 5 of the chromosomes condense in advance of the remaining 5, 

 and can always be distinguished from the other chromosomes. There is no indication of a 

 tetrad formation. In the 1st division all chromosomes divide and each daughter cell receives 

 10. In the 2nd division there is no chromosomal division but merely a separation of the 

 chromosomes into 2 groups, those which were condensed first going to one pole and the others 

 going to the other, thus giving rise to 2 kinds of spermatids each containing 5 chromosomes. 

 Spermatozoa formation seems to follow normally. — Mary T. Ilarman. 



124. Seiler, J. [German rev. of: Mohr, Otto L. Mikroskopische Untersuchungen 

 zu Experimenten iiber den Einfluss der Radiumstrahlen und der Kaltewirkung auf die Chro- 

 matinreifung und das Heterochromosome bei Decticus verruccivorus (cf ). (Microscopic 

 studies relating to experiments on the influence of radium rays and effect of cold on maturation 

 and the heterochromosome of Decticus verruccivorus (d^)-) Arch. Mikrosk. Anat. 92: 

 300-3G8. 6 pi. 1919.] Arch. Zellforsch. 15: 312. 1920. 



125. Shamel, A. D. Cooperative improvement of citrus varieties. California Citrograph 

 6: 141, ISG, 199, 220-222. 7 Jig. 1921.— A general discussion of "bud variation" and "bud 



