No. 1, November, 1921] HORTICULTUBE 29 



fixed since there will be a degree of inbreeding consequent upon small numbers. If selection 

 is directed toward a type between a mean and one of the extremes almost the full effect of 

 selection is reached in the 1st generation and further selection merely reduces the variability 

 slightl3^ If all the variation is not due to genetic causes, the usual condition, the point will 

 be reached below which variation can not be reduced and selection therefore becomes con- 

 tinually more ineffective. — Edward N. Wentivorth. 



147. Wright, Sewall. Systems of mating. V. General considerations. Genetics 6: 

 167-178. 7 fig. 1921. — In this paper the author discusses some of the more important results 

 of his previous papers (see the preceding 4 entries) unencumbered by mathematics. He 

 shows that with random mating, inbreeding, or assortative mating, the relative frequency of 

 the different genetic factors in the original population remains constant in any subsequent 

 descendant population as a whole and random breeding restores the original composition. 

 On the other hand, selection which is due to a differential rate of reproduction among different 

 classes modifies the relative frequencies of genetic factors and effects a permanent change. 

 The combination of all systems of mating he has studied is shown to be the most effective 

 way of modifying the characteristics of a stock. Charts showing the differential rates of 

 progress under different systems of mating are presented. The rate of obtaining homozygosis 

 is considered important since it measures the permanency of the change effected by the system 

 of mating and is a very important quality in increasing prepotency. It is shown that selection 

 produces progress toward perfect homozygosis only when directed toward an extreme type. 

 Close inbreeding or assortative mating leads to increased variability in the population as a 

 whole while disassortative mating holds the population together. Matings between relatives 

 more remote than first cousins have little significance as inbreeding unless the population is 

 small. — Edward N . Wentworth. 



148. ZiEGLER, A. Unterscheidungsmerkmale der Gerste mit besonderer Beriicksichtig- 

 ung der Basalborste. [Distinguishing characters of barley with special reference to the basal 

 bristles.] Deutsch. Landw. Presse 47: 184-185. 1920. — A description is given of 2 types of 

 basal bristle in 2-rowed barley: Type A, hairs long, sharp-pointed, single-celled; type C, hairs 

 shorter, branched, blunt, and usually several-celled. The author finds non-heritable varia- 

 tions within the type, but the types themselves are well separated by these distinguishing 

 characters. — F. P. Bussell. 



HORTICULTURE 



J. H. GouRLEY, Editor 

 H. E. Knowlton, Assistant Editor 



(See also in this issue Entries 28, 84, 85, 99, 125, 126, 127, 128, 129, 140, 211, 231, 



248, 294, 295, 303, 314, 319, 38l) 



FRUITS AND GENERAL HORTICULTURE 



149. Anonymous. [Rev. of: Copeland, E. B. The coconut. 2nd ed. revised, xvi 

 + ns p. Macmillan and Co.: London, 1921.] Nature 107: 391. 1921. 



150. Allen, R. H. Eighteenth annual report of the state nursery inspector. Massachu- 

 setts State Nursery Inspector Ann. Kept. 18: 1-12. 1920. — One hundred and forty eight nurs- 

 eries were inspected and certificates issued, also200 shipments of foreign stock were examined. 

 A list of the insects and fungous diseases found is given. Work in the control of white pine 

 blister rust was carried on in cooperation with the U. S. Department of Agriculture. Eradica- 

 tion of Ribes in the southeastern area was continued, and through financial aid from the 

 State Forestry Department and private sources further work in Petersham and other towns 

 was carried on. A tabulated summary of the work done and costs is given. The European 

 corn borer was found in extended areas and the work of eradication in infested areas and main- 

 taining a quarantine against these areas continued. — /. A'. Shaw. 



