No. 2, June, 1921] GENETICS 165 



against less than 1 per cent fruit in short-style selfings (159 pollinations gave one fruit). 

 Fruits in both cases have good seed. Results in P. elatior somewhat similar. Illegitimate 

 pollinations of long-style P. acaulis X long-style P. elatior gave no results. Illegitimate 

 pollinations of P. Sibthorpii X P. elatior and of P. Auricula gave only negative results. 

 Legitimate unions in P. acaulis, P. acaulis X P. Sibthorpii, and reciprocals fruit readily and 

 seed is similar in all in number, size, and weight. Fi P. acaulis X P. Sibthorpii is fertile and 

 crosses back with either parent. Legitimate unions of P. acaulis X P. elatior are more diffi- 

 cult to secure than legitimate unions between plants of P. acaulis, but less difficult than 

 illegitimate unions. Fruit and seed in general are very small and seed weight at most half 

 that of seed of pure species. Reciprocal (P. elatior X P. acaulis) in legitimate cross-pollina- 

 tion sets fruits readily and gives 50-60 per cent very large seed, and remainder very light. 

 Legitimate cross-pollination of P. acaulis by P. Juliae produces fruit as readily as legitimate 

 unions in P. acaulis, but seeds, though equal in number, are lighter and smaller. Fi hybrids 

 are fertile. Fi back-crossed with parents in legitimate unions gave seed as large and numer- 

 ous as in P. acaulis. P. elatior fruits readily in legitimate cross-pollination. Legitimate 

 cross-pollination of P. elatior by P. Sibthorpii gives results similar to P. elatior X P. acaulis. 

 Reciprocal crosses (12) gave only one fruit with very small seeds. Long-style P. elatior X P. 

 Juliae short-style, fruited and seeded as readily as pure P. elatior in legitimate unions. Fi 

 hybrids are fertile in legitimate unions. Both style-forms of P. Auricula in legitimate 

 unions set fruit readily. Legitimate crosses of P. Auricula by P. hirsuta and reciprocal set 

 easily. Legitimate crosses between plants of P. hirsuta are fertile. Seeds of P. Auricula, 

 P. hirsuta and their hj^brids from legitimate unions are indistinguishable. Literature on the 

 subject is reviewed. — Orland E,. White. 



1125. White, William A. [Rev. of: Knight, M. M., Iva, L. Peters, and Phyllis 

 Blan CHARD. Taboo and genetics. SOI p. Moffat, Yard and Co.: New York, 1920.] Mental 

 Hygiene 5: 194-195. 1921. 



1126. Wright, Sew all. The relative importance of heredity and environment in deter- 

 mining the piebald pattern of guinea-pigs. Proc. Nation. Acad. Sci. [U. S.] 6: 320-332. 6 Jig. 

 June, 1920.— Correlation between parents and offspring was found to be -f- 0.211 =*= 0.015 for 

 random-bred stock with piebald pattern, while it was found to be only + 0.014 =*= 0.022 for 

 stock inbred for many generations. Variability in inbred stock is thought to be due almost 

 entirely to irregularity in development. By biometrical methods it has been determined 

 that for the random-bred stock "variations in pattern are determined about 42 per cent by 

 heredity, and 58 per cent by irregularity in development, leaving nothing for tangible environ- 

 mental factors. In the inbred family the corresponding figures are 3 per cent for heredity, 

 5 per cent for tangible environment, and 92 per cent for irregularity in development." — 

 H. L. Ibsen. 



1127. Yampolsky, Cecil. Sex intergradation in the flowers of Mercurialis annua. Amer. 

 Jour. Bot. 7: 95-100. 1 pi. Mar., 1920.— Typical flowers for male, female, and monoecious 

 forms in this species are described, and various grades of hermaphrodite flowers are described 

 and figured for both female and monoecious forms. These develop in various grades of 

 maleness along with complete femaleness, or in various gradations in the proportion of the 

 two, with in many cases no loss of functioning power of the organs formed. "Most elaborate 

 and varied transition stages appeared of stamens into pistils and of pistils into stamens." 

 "Intergradations within the flowers may occur by steps that are almost insensible." A 

 periodic alteration of sex is reported for monoecious plants. — It is pointed out that a fac- 

 torial hypothesis of sex determination does not explain these results; that no definite factor 

 determines the sex of a flower, but that sex is here an epigenetic condition. — A. B. Stout. 



