32 GENETICS [Bot. Absts. 



228. Anonymous. Inheritance of characters in the culinary pea. [Rev. of: White, 0. E. 

 Studies of inheritance in Pisum. II. The present state of knowledge of heredity and varia- 

 tion in peas. Proc. Amer. Phil. Soc. 56:487-588. 1917.] Gard. Chron. 65:230. May 10, 

 1919. 



229. Bateson, W. Studies in variegation. I. Jour. Genetics 8:93-99. PL 8-4, 1 fig. 

 Apr., 1919.— See Bot. Absts. 3, Entry 594. 



230. Becking, L.G.M. Baas. Some numerical proportions in panmictic populations. Rec. 

 Trav. Bot. Neerland. 15:337-366. 1 pi. 1918. — As Hardy, Pearson, Jennings, and others, 

 pointed out, the population R AA + S Aa + T aa will remain constant in its proportions 

 after a number of random matings. Pearson's "Law of ancestral heredity" as applied to 

 Mendelian populations is based upon this fact only. Now, Pearson's Law cannot be general- 

 ized. As writer points out a population with random mating (so-called panmictic population) 

 does not remain constant in its proportions if there are two or more than two genotypic dif- 

 ferences. Formulae for the different constituent groups are easily derived. Writer has done 

 so for a digene population. The formulae obtained give rise to many particular consequences. 

 In the first place we can prove that the population reaches a limiting value after a great number 

 of generations, the homozygotes being proportional in pairs. This limiting population 

 remains constant in its constitution. The constitution of the original population is of no 

 influence on that limiting form. These qualities are also true for populations with more than 

 two genotypic differences. — In the second place it is easily proved that if the homozygotes. 

 are equal in pairs, they will be all equal to each other after a great number of generation : 

 Thirdly: if in a certain population the number of the homozygotes : mono-heterozygotes : 

 di-heterozygotes : n-heterozygotes = 1 : 2 : 2 2 : 2 n , that population will be constant in 

 its constitution. The formulae are treated also geometrically, this method demonstrating 

 clearly the fact that all populations will reach the same limiting value. It seems of impor- 

 tance to take wild populations (e.g., endemic populations on small islands) as an object of 

 inquiry to test the value of the formulae. If there is panmictic mating in that population, 

 there must exist certain numerical relations between the different genotypic constituents. 

 The random mating, being the most general case of syngamy, thus offers a good starting point 

 for mathematical investigation of Mendelism. — L. Baas Becking. 



231. Best, Harry. The blind: their condition and the work being done for them in the 

 United States. 20 X 15 cm., xxi + 763 p. Macmillan Co. : New York. 1919.— Comprehensive 

 treatise in which chapter 7 (p. 126-154) deals with "Blindness and heredity." From census 

 of 1910 it is found that 24.1 per cent of all blind have near relatives who are also blind. Sim- 

 ilar results are also presented from reports of various schools for the blind. Analysis of 

 causes of hereditary blindness indicates that they are for most part specific affections of the 

 eye. Most notable of these is cataract, of which there are several different hereditary forms. 

 Other diseases having strong hereditary tendencies are glaucoma, retinitis pigmentosa, 

 detachment of the retina, one form of atrophy of optic nerve, etc. A number of diseases which 

 occasionally result in blindness, also show marked influence of heredity. Author considers 

 effect of marriage of blind inter se. Quotes census report showing that blindness is handicap 

 to marriage, the proportion of married among the blind 15 years old or over being about 89 

 per cent of normal. This handicap is especially effective when blindness occurs before age 

 of 20 years. Data on marriage between two blind persons are not available in census reports 

 but direct inquiry indicates presence of several hundred couples in United States of America, 

 who were both blind at time of marriage. On very limited information concerning these 

 families, conclusion is reached that two blind parents do not necessarily have more blind 

 children than a mating between a blind and a normal person. This statistical result is 

 explained on basis of fact that blindness is result of many independent causes, so that in mat- 

 ings between two blind persons there is still no case in which both parents are blind for same 

 cause. — In some families consanguineous marriages considerably increase proportion of blind 

 progeny while in other families no such result is found. Advocates eugenical laws and edu- 

 cation directed toward the elimination of diseases which are known to be correlated with 

 hereditary blindness. — G. H. Shull. 



