392 



SCIENCE 



[N. S. Vol. XLII. No. 1081 



we represent is second to none in the importance 

 ■which it has for society, and I therefore look on 

 the growing tendency to lift this above the lay- 

 man's comprehension as a calamity, in which I 

 hope the Journal of Heredity will have no share. ' ' 



Dr. Herbert J. Webber, of the University of 

 California, who spoke on ' ' Science m the Prac- 

 tise of Plant Breeding," remarked that the effect 

 of the rediscovery of Mendel's Laws had often 

 been over-emphasized. It had clarified our views, 

 but as a fact, the segregation of characters in the 

 second filial generation of a cross was well-known 

 to breeders previous to 1900, and they used this 

 knowledge constantly in their work. He empha- 

 sized the great opportunities offered to breeders 

 by the immense number of possible combinations 

 of unit characters, and declared that more genet- 

 icists should attack the great problem of the origin 

 of variations — the fundamental problem of breed- 

 ing, but one which most experimental breeders 

 were neglecting. The pure line theory, he de- 

 clared, offered a chance for reconciling the con- 

 flicting views of the selectionist and the hybrid- 

 ist. He urged that practical breeders should make 

 themselves more familiar with morphology and cy- 

 tology. 



Bob E. Slocum, of the U. S. Department of 

 Agriculture, presented a review of experimental 

 work in poultry breeding, and declared that the 

 results of this work did not materially modify the 

 procedure which intelligent poultrymen had been 

 accustomed to follow for many years. One of the 

 greatest practical results of genetic research in 

 poultry, he thought, was to encourage poultrymen 

 to keep more accurate pedigrees of their fowls. 

 His paper was illustrated by motion pictures. 



E. D. Ball and Byron Alder, of the Utah Ex- 

 periment Station, discussed the question "Is Egg- 

 laying in the White Leghorn a Unit Character?' 

 The results of their experiments at Logan, Utah 

 during seven years showed them that the first 

 year egg production of a hen is no reliable meas 

 ure of what she will do in succeeding years, and 

 that winter egg-production is not a proper meas- 

 ure of a hen's fecundity, being even more subject 

 to environmental influences than yearly totals. 

 They decided that no evidence hitherto presented 

 by any one was adequate to answer the question 

 whether egg-laying is a unit character. 



Leon J. Cole and Frank J. Kelley, of the Uni- 

 versity of Wisconsin, described their experimental 

 breeding work on dominant and recessive red in 

 pigeons. The red color found in uniformly col- 

 ored tumbler pigeons was found by Cole some 



years ago to be a simple Mendelian recessive to 

 black. Another factor has been found, however, 

 which hag the capacity of altering the expression 

 of black; so that birds carrying the factor for 

 black, if they also carry this second factor, often 

 have a distinct reddish appearance superficially re- 

 sembling those individuals which are red because 

 of the absence of black. This aecond factor is sex- 

 linked. 



W. S. Anderson, of the University of Kentucky, 

 described his work in the investigation of horse 

 breeding. Aside from the attack of such prac- 

 tical problems as sterility, he has investigated the 

 lines of descent of the most famous American 

 trotting stallions, and found that thousands ' ' run 

 out," to every one which shows on-breeding ca- 

 pacity. The importance of the dam was empha- 

 sized in this connection. Following Professor 

 Anderson's paper, motion pictures of the horse 

 breeding of the Bureau of Animal Husbandry, U. 

 S. Department of Agriculture, were shown. 



H. B. Frost, of the University of California, de- 

 scribed mutation in Mathiola annua, a ' ' Mendel- 

 izing ' ' species, and reported on tests of pedigree- 

 culture methods in Southern California. 



B. O. Cowan, of Santa Monica, Calif., whose 

 subject was "Inbreeding," concluded: "That in- 

 breeding of live stock has brought very beneficial 

 results can not be denied; that it is a source of 

 danger is equally true; so if practised at all, it 

 should be with the greatest discretion." 



R. Buggies Gates, of the University of London, 

 spoke on "Successive Duplicate Mutations." 

 Nilsson-Ehle first found duplicate and triplicate 

 factors for red in wheat. Some races were found 

 to have a single factor, giving only ratios 3 red: 

 1 white, others had two factors and hence gave 

 also 15: 1 ratios, while still others gave also 63: 1 

 ratios and hence possessed three factors. It is 

 suggested that this condition originated through 

 mutation or chemical change having first taken 

 place in one chromosome or pair of chromosomes. 

 This gave the 3:1 condition. The duplicate con- 

 dition arose from this afterwards, either through a 

 similar change in another chromosome, or more 

 probably by a mechanical re-mating of the chromo- 

 some pairs, thus giving 15: 1 ratios. CEnothera 

 ruhricalyx similarly originated as a monohybrid 

 through a chemical change in a chromosome, but 

 some of the later generations have become dihybrid 

 (giving 15: 1 ratios) by a re-mating of the chro- 

 mosomes. This rearrangement probably occurs at 

 the time of fertilization rather than during 

 meiosis. 



