30 GENETICS [BoT. Absts., Vol. VIII, 



222. Bannier, J. P. [Dutch rev. of: Hagem, Oscar. Einige F2 und F3 Generationen 

 bei dem Bastard Medicago sativa X M. falcata. (Some F2 and F3 generations of the hybrid 

 Medicago sativa X M. falcata.) Nyt Mag. Naturvidenskab. 56: 149-165. 1919.] Genetica 2: 

 535-536. 1920. 



223. Bannier, J. P. [Dutch rev. of: (1) Yampolsky, Cecil. Inheritance of sex in Mer- 

 curialis annua. Amer. Jour. Bot. 6:410-442. PI. 37-40, 1 fig. 1919. (See Bot. Absts. 4, 

 Entry 827.) (2). Idem. The occurrence and inheritance of sex intergradation in plants. 

 Amer. Jour. Bot. 7:21-38. 1920. (See Bot. Absts. 5, Entry 502.) (3). Idem. Sex inter- 

 gradation in the flowers of Mercurialis annua. Amer. Jour. Bot. 7 : 95-100. 1 pi. 1920. 

 (4). Idem. Further observations on sex in Mercurialis annua. Amer. Nat. 54: 280-284. 

 1 fig. 1920. (See Bot. Absts. 6, Entry 750.)] Genetica 2 : 554-556. 1920. 



224. Banta, Arthur M. Selection in Cladocera. [Abstract.] Anat. Rec. 20: 212. 

 1921. — Some years ago the writer undertook experiments in selection in parthenogenetic pure 

 lines of Cladocera on the basis of a purely physiological character, reactiveness to light. 

 Sixteen lines were subjected to selection for various periods extending over from 18 to 196 

 generations. In 7 of these lines no difference appeared in reactiveness between the 2 strains 

 of the same line. In 2 lines slight divergences in reactiveness were in the reverse of selection. 

 These divergences, while not large, were fairly consistent. In 1 of these cases the divergence 

 decreased as the experiment progressed. In 5 lines there was a possible effect of selection but 

 the evidence is not considered conclusive. In 2 lines an effect of selection is rather clearly 

 indicated. In 1 of these the divergence was not large and this case may be disregarded. 

 But in the other the effect of selection is very large and is clearly substantiated. The diver- 

 gence in this line appeared slowly and increased gradually until during the last months of the 

 experiment the reaction time of the low strain was less than a third that of the high strain. 

 The difference in reactiveness to light was permanent or at any rate persisted for 32 months 

 (112 generations) after selection was discontinued. Return selection was not attempted. — 

 A 2nd series of selection experiments based on an entirely different character is now under 

 way. The character used is the degree of intergradedness of sex intergrade strains of Daphnia 

 longispina. Derived from a common progenitor and reproducing solely by parthenogenesis 

 this would seem a most excellent material for a study of selection. Three strains were selected 

 as high strains and 3 as low strains, the high and low strains being taken alternately 

 from the 6 available sister strains. Selection was effective in each case, the individuals of 

 the high strains becoming as high (i.e., as male) as they could be maintained with fair repro- 

 ductive ability; and the low strains approaching very nearly the condition in which sex inter- 

 gradedness is not apparent, i.e., most of the individuals showed no sex intergrade characters 

 and the few intergrades were slightly affected. While the facts are as stated, environmental 

 or other factors are influential to such an extent that the curves for the different strains fluc- 

 tuate somewhat. Further, selection is not effective with equal promptness in every strain 

 though in all cases it has ultimately been effective. Return selection is also effective. 

 Through selection low strains have been derived from the selected high strains, and high 

 strains from the selected low strains. Two strains have in turn been selected low strains, 

 selected high strains, and selected low strains again. — Thus selection and return selection are 

 equally effective with the amount or degree of sex intergradedness in Daphnia longispina. — 

 Arthur M, Banta. 



225. Bartsch, p. Experiments in the breeding of Cerions. Carnegie Inst. Washington 

 Publ. 282. 65 p., 59 pi. Washington, 1920. — These land shells are extremely non-roving and 

 are well adapted to breeding experiments in which isolation in different regions is a 

 feature. Author planted four Cerion species from the Bahamas on the Florida keys. From . 

 several of the many colonies (usually containing 500 to several thousand marked shells) 

 numerous first generation Florida-grown offspring have been obtained. In several cases 

 lots of first generation offspring were transplanted and known second generation Florida- 

 grown offspring secured. Differences in internal structural features in the different species 



