No. 3, July, 1921] GENETICS 275 



American Society of Naturalists, and is a constructive attempt to promote an established 

 system in genetic usage, particularly of symbols for the representation of factors. The 

 report makes the following suggestions: (1) That a type (the wild when possible) be named, 

 and that genetic factors in general be measured by their departure from this. (2) That mem- 

 bers of an allelomorphic series dominant to the type be designated by the same symbol as 

 the type in capitals and with appropriate superscripts, and that recessive members have the 

 same symbol in lower case with superscripts. (3) That dominance be recognized by departure 

 from type in the heterozygote. (4) That in addition to literal (mnemonic) superscripts, 

 numerical superscripts may also be used to indicate the relative degree of departure from type 

 of each member of the allelomorphic series. (5) Independent allelomorphs or allelomorphic 

 series may be represented by different letters, or, where they produce similar effects, by the 

 same letter followed by a designating numeral. (6) "Doubtful factors," whose presence is 

 uncertain, may be represented by their respective symbols with superscript x or ?. 

 (7) The presence of modifiers of the effect of any factor may be represented by the symbol 

 [+]; thus [S+] may represent "+ modifiers of the effect produced by the S (spotting) series of 

 allelomorphs," and when it is desired to express the degree of modification, numbers may be 

 used for that purpose, as [+4.2] or [—2.5]. (8) "Linkage is best represented by the fractional 

 form used by workers on Drosophila." — The report is published in the hope that it will stimu- 

 late discussion and suggestions. — L. J. Cole. 



1929. McCandlish, A. C. Environment and breeding as factors influencing milk pro- 

 duction. Jour. Heredity 11 : 204-214. Fig. 6-15. 1920. — An account of an experiment at the 

 Iowa Agricultural Experiment Station to demonstrate the possibilities of improving a scrub 

 herd. The animals used were inferior as a dairy type and were low producers. These cows 

 were put in with the Station herd and given the same feed and care as the pure breeds. Care- 

 ful milk and butter-fat records were kept as guides to feeding methods. The scrub cows 

 were mated to pure-bred sires of Holstein, Guernsey and Jersey breeds and the heifer calves 

 resulting were maintained under the same conditions as the other animals. Records are now 

 available on 2 generations of grades descended from scrub cows and 1 animal of the next 

 generation has just entered the herd. The influence of environment upon production is 

 shown by the records. When the scrub cows that came to the station after reaching maturity 

 are compared with those coming at 4 years of age and with those coming before the first fresh- 

 ening, it was found that the former produced 14 per cent more'milk and 8 per cent more fat, 

 and the latter 27 per cent more milk and 24 per cent more fat. Scrub bulls will give no im- 

 provement in the production of a herd. Pure bred sires on the other hand showed a marked 

 improvement in production in both the 1st generation and 2nd generation grades. The 

 1st generation taken as a group showed increases of 39 and 37 per cent in milk and fat produc- 

 tion respectively when compared with their dams, and the 2nd generation, so compared, 

 increases of 116 and 106 per cent respectively in milk and fat production. Both breeding and 

 environment are thus shown to be important factors in production. — M. J . Dorsey. 



1930. McRosTiE, G. P. Inheritance of disease resistance in the common bean. Jour. 

 Amer. Soc. Agron. 13: 15-32. 1921. — Crosses between varieties of beans resistant to a and 

 /3 strains of Colletotrichum lindemuthianum and 1 susceptible to a strain only, indicate that 

 resistance to a strain is due to a single factor and is dominant. Crosses between a variety 

 resistant* to both strains and 2 varieties susceptible to both strains showed a 2-factor basis 

 for resistance to both strains of the anthracnose fungus. In F2 a 9:7 ratio was obtained. 

 Significant variations in individual F2 families are said to be due to difficulty in obtaining 

 uniform conditions for infection in large outside inoculation chamber. Crosses between 

 Robust Pea bean, highly resistant to mosaic disease, and of Flat Marrow bean, which is very 

 susceptible, indicate 2 factors in homozygous state necessary for complete susceptibility. 

 Absence of both factors gives high degree of resistance. One plant in 16 of F2 generation 

 of 5272 plants was severely infected. All gradations between resistance and susceptibility 

 occurred. Susceptibility showed only partial dominance. Crosses between Flat Marrow, 

 resistant, and Robust Pea, susceptible to root rot {Fusarium martii phaseoli), indicated in 



