No. 2, March, 1921] GENETICS 129 



ship between classes of streptococci, and their source, habits, pathogenicity, or other char- 

 acteristics. More than 160 strains were isolated from various sources, pathogenic and non- 

 pathogenic. Cultural characteristics were ascertained from growth on different media, 

 chiefly blood agar, carbohydrates and salicin. Agglutination and complement fixation were 

 applied. — Author concludes that no relationship of source, habitat, or pathogenicity, of the 

 streptococci classes was established; a basis of classification is lacking.— Morphology and car- 

 bohydrate fermentation is variable; hemolysis is fairly constant; the hemolytic group is 

 heterogeneous; agglutination shows a high degree of uniformity.— Andrew /. Dawson. 



870. Cleaver, S. M. Merino history and merino breeding. 15 X 23 cm., 48 p., SS fig. 

 S. M. Cleaver: Delaware, Ohio, 1918.— A popular account of the history of Merino sheep 

 breeding in America, with a discussion of the various types which have been developed and 

 the difficulties met in trying to combine all good qualities in one type. — Sewall Wright. 



871. CoRRENS, C. Eine gegliickte Verschiebung des Geschlechtsverhaltnisses. Botan- 

 ische Versuche zur Frage nach der Entstehung des Geschlechts. [A successful modification 

 of the sex-ratio. Botanical researches on the origin of sex.] Natur u. Technik 2:65-71. 

 2 fig. 1920.— Review of sex determination in animals and plants and experiments on the 

 dioecious plant M eland rium (Lychnis) which show that the staminate plants are heterog- 

 amous and the pistillate homogamous. Results agree with those of Strasburger and 

 of Shull in showing excess of pistillate over staminate plants. Deficient amount of pollen 

 applied also resulted in excess of pistillate plants but when large excess of pollen (more than 

 100 grains per ovule) was applied, so that competition between male- and female-determining 

 gametes took place, there was even greater excess of pistillate plants: 44 to 56 per hundred 

 in the first case and 32 to 68 per hundred in the second. A moderate excess of pollen of 7 

 grains to 1 ovule gave an intermediate ratio of 40 to 60.— The faster growth of the female- 

 determining pollen tubes was also shown by comparing the seeds from the top half with those 

 from the bottom half of the same capsule. The seeds resulting from the shorter growth of 

 pollen tubes gave 68, and the seeds from the longer growth 56, per cent pistillate plants. In 

 this plant the pollen tubes enter the ovary at a common point and are all free to fertilize 

 the first ovules to be reached. This was tested by pollinating a white-flowered plant with a 

 small quantity of pollen from a red-flowered plant and 24 hours later with pollen from a 

 white-flowered plant: 71 per cent of the crossed, red-flowered plants came from seeds out of 

 the upper third of capsule as compared to 29 per cent from the lower two thirds. Conclusion: 

 Unequal production of heterogametes and unequal rate of growth of pollen tubes modifies 

 sex-ratio in Melandrium. — D. F. Jones. 



872. Crandall, C. S. Observations on characters of forms of Malus. Proc. Amer. Soc. 

 Hortic. Sci. 16 (1919) : 131-135. 1920.— The writer bases his observations on 44 standard 

 horticultural varieties and 45 crab forms, and upon 495 parental combinations of them. 

 Most botanical characters of genus are variable. "Petals, 5:" Vary from 4 to 8. Seedlings of 

 variable parent had 10. "Carpels, 2 to 5:" Four out of 32 varieties had constantly 5 carpels; 

 two out of 28 crabs had constantly 5 carpels; in M. Mains fl. pi.— 81 per cent of fruits varied 

 from 5 to 9 carpels; in M. speciabilis 87 per cent had 5 to 12 carpels; in M. Arnoldiana 99 per 

 cent and in M. atrosanguinea 96 per cent had less than 5 and one of each had 2 carpels. Of 

 6000 fruits from 23 crab forms, 33.95 per cent varied from 5 carpels. "Ovules, 2 per carpel:" 

 Of 21 standard varieties, only 2 were constant, the variation averaging 8.23 per cent with a 

 maximum of 84.63 per cent. In crabs (25 varieties and species) 12 were constant. In 4 forms, 

 ovules were suppressed, from 1 to lb less than normal. In remainder there was an excess of 

 ovules from 1 in Yellow Siberian Crab to 300 in M. spectabilis. "Calyx lobes persistent or 

 deciduous:" This is a distinctive varietal and specific character. Most cultivated varieties 

 are persistent. Of 41 crab forms, 16 were deciduous, 13, persistent, and in 12, part on each 

 tree were deciduous and part persistent. The writer believes that the instability of this 

 character in most crab forms indicates their hybrid origin. — In Fi of large leaf X large leaf 

 and small leaf X small leaf (standard varieties), there is a predominance of large-leafed 

 forms, with some small and some intermediate. When large-fruited forms were crossed with 



