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



Fi that susceptibility is partially dominant. A condition midway betweeti that of plants 

 showing greatest infection in any particular season and normal condition of healthy plants 

 was chosen to separate classes. F2 data were checked by growing F2 families. A 2-factor 

 basis in relation to root rot is indicated. Strains of commercial value resistant to both 

 mosaic and root rot have beeti selected. On account of their parentage all of these should 

 be resistant to/3 strain of C. lindemuthianum. — J. P. Shelton. 



1931. Mathews, J. Wkenford. Sheep and wool for farmers. Cross-breeding experi- 

 ments. Results of lamb-raising trials. Agric. Gaz. New South Wales 31: 761-770, 84C-S52. 

 10 fig. 1920. — In previous experiments, rams of various long-wool breeds had been crossed 

 with Merino ewes to determine which combination resulted in the greatest aggregate value 

 of wool and mutton. None of the combinations produced lambs suitable for the export lamb 

 trade. The present papers discuss in detail the results of crosses between rams of 3 short- 

 wool breeds with ewes from 3 long-wool-Merino crosses. Good lambs were produced by all, 

 but Dorset Horn rams sired consistently heavier lambs than Shropshires or Southdowns, 

 and the Border-Leicester cross ewes were consistently superior to the Lincoln or Leicester 

 crosses. — Seivall Wright. 



1932. Osgood, Wilfred H. The turkey as a subject for experiment. Amer. Nat. 55: 

 84-88. 1921. — Author states that there is little genetic work under way "which can be cor- 

 related logically with the results of speciation and subspeciation as the field naturalist and 

 taxonomist find them in nature." He thinks the 6 races or subspecies of the American turkey 

 would furnish excellent material for this purpose. If it could be shown that the differences 

 between these "behave as hereditary units without any such blending as requires 'dialectic 

 gymnastics' to explain, it would be a long step forward in the correlation of natural and man- 

 made experiments." — William A. Lippincott. 



(I 



1933. Payne, Fernandus. Selection for high and low bristle number in the mutant strain 

 reduced." Genetics 5: 501-542. 3 fig. Nov., 1920. — In the 6th generation of selection for 



increase in scutellar bristles in a race of Drosophila melanogaster a male appeared with only a 

 single bristle. Starting with the "reduced" strain originated by this fly, plus and minus 

 selection lines were carried on by inbreeding for 60 and 65 generations, respectively, including 

 counts of over 200,000 flies. As in results previously reported by author, in which similar 

 selection lines were started from variations in wild stock, this selection isolated 2 distinct 

 lines. The sorting process was clearly effective for about 18 generations, after which slight 

 progress was made, although no somatic limit had been reached. Minus line continued to 

 produce a few flies with 1 bristle ; plus line, a few flies with no bristles. These 2 lines are shown 

 to be genetically distinct by failure of return selections, by maintenance of their differences 

 in mass cultures, and by crosses. It is concluded from linkage tests that a single sex-linked 

 factor differentiates the "reduced" strain as a whole from wild strains; that plus and minus 

 lines within the "reduced" strains differ genetically by 2 plus modifiers, 1 of which is in sex 

 chromosome near miniature, the other in 3rd chromosome near sepia. These modifiers can 

 be passed over to wild selection for high and low bristle number in Drosophila, and so produce 

 an extra-bristle race. Author considers this investigation "another link in the chain of 

 accumulating evidence in favor of the multiple-factor hypothesis as an explanation of the 

 effects of selection in bisexual forms." — E. Carleton MacDowell. 



1934. Pelseneer, Paul. L'hybridation chez les mollusques. [Hybridization among mol- 

 lusks.] Compt. Rend. Acad. Sci. Paris 168: 1056-1059. 1919. — Controlled observations of 

 hybridization among mollusks, occasioned by designation in conchological literature of cer- 

 tain types of individuals as hybrids. In fluviatic forms copulation was observed in various 

 combinations of Limnaea. Eggs, egg masses, embryos, and young exhibited exclusively 

 maternal characters. Foreign sperm merely induces development without fertilization. Ex- 

 amination showed retention of an undivided polar body until gastrula stage. In reciprocal 

 crosses of marine forms, Pholas Candida (lamellibranch) X Patella vulgata (gastropod), 

 larvae conformed to maternal type. In reciprocal crosses of Pholas Candida X Hermella 



