220 



SCIENCE 



[N. S. Vol. XL VI. No. 1183 



APRIL 13 



George EUery Hale, Ph.D., Sc.D., LL.D., F.E.S., 



Vice-president, in the chair 

 Lighting in its relation to the eye: Clarence E. 



Ferree, Ph.D., professor of psychology, Bryn 



Mawr College. (Introduced by Dr. W. W. 



Keen.) 



The work of which this paper is a brief outline 

 was done under the auspices of the American Med- 

 ical Association's subcommittee on the hygiene of 

 the eye, of which Dr. "William Campbell Posey, of 

 this city, is chairman. The object of the work has 

 been to compare the effect of different lighting 

 conditions on the eye and to find the factors in a 

 given lighting situation which cause the eye to lose 

 in ef&cieney and to experience discomfort. In all, 

 forty-two different lighting situations have been 

 investigated, selected with special reference to the 

 problem in hand. Also a number of miscellaneous 

 experiments have been conducted pertaining to the 

 hygienic employment of the eye. Tests were made 

 to determine the eye's aggregate loss in func- 

 tional activity and to analyze this effect. In all 

 seven different types of tests were used. 



Factors influencing the sex ratio in the domestic 

 fowl: Raymond Pearl, Ph.D., biologist, Maine 

 Agricultural Experiment Station, Orono, Maine. 

 The problem of the sex ratio is one of the most 

 important of biology from the theoretical stand- 

 point as well as from that of the practical breeder 

 or farmer. The desire to control the proportions 

 of the sexes produced is one which has excited 

 mankind through the ages. Thanks primarily to 

 the work of certain American biologists, notably 

 Professor C. E. McClung, of the University of 

 Pennsylvania, and Professor E. B. Wilson, of Co- 

 lumbia University, the key to the riddle of sex has 

 at last been found. It is well known that in a wide 

 Tange of animals there is a definite hereditary 

 mechanism which irrevocably determines the sex 

 of the individual. While it is true that a definite 

 mechanism controls the determination of sex, yet 

 there has appeared a great deal of evidence re- 

 cently, of varying degrees of trustworthiness, that 

 sex ratios may be experimentally modified and eon- 

 trolled. It is the purpose of this paper to examine 

 the sex production question in the common fowl, 

 and see to what conclusions it leads. In the pres- 

 ent war conditions any information which would 

 make it possible for the poultryman or farmer to 

 produce a larger number of pullets to lay eggs 

 without producing so many cockerels to eat up 

 costly food, would be of very great value. This 



study, which is based on eight years' experiments, 

 and over 22,000 individuals, demonstrates first 

 that the determination of sex in poultry is pri- 

 marily a matter of a definite, hereditary mechan- 

 ism, just as it is in insects and other forms which 

 have been studied. At the same time, it is dem- 

 onstrated that under certain physiological circum- 

 stances the operation of this mechanism may be 

 modified in such a way as to lead to the produc- 

 tion of more females, in proportion to the number 

 of males. The chief factor in bringing about the 

 modification in the direction of a larger produc- 

 tion of females is the fecundity or laying ability 

 of the hens used as breeders. The larger the num- 

 ber of eggs which a hen lays before being put into 

 the breeding pen, the larger will be the proportion 

 of females and the smaller the proportion of 

 males produced by her eggs. Some years ago it 

 was shown by the speaker that the ability to lay 

 eggs (fecundity) in poultry is a matter of definite 

 Mendelian inheritance. As a result of this knowl- 

 edge, it is possible to breed strains of hens in 

 which high productivity is a definitely fixed char- 

 acteristic. The present results taken in connec- 

 tion with the earlier ones show that when the 

 poultryman breeds along the right lines for in- 

 creased egg production, he will at the same time 

 be producing a strain in which profit making 

 pullets preponderate in place of the less profitable 

 cockerels. 



Significant results of scientific investigations ap- 

 plied to fishery problems: Hugh M. Smith, 

 M.D., LL.D., commissioner of fisheries, Wash- 

 ington, D. C. (Introduced by Dr. Clarence E. 

 McClung.) 

 A description of a new photographic transit instru- 

 ment : Frank Schlesinger, Ph.D., director of 

 the Allegheny Observatory, University of Pitts- 

 burgh. 



In many departments of astronomy it has been 

 found that visual methods can advantageously be 

 replaced by photographic. This experiment is an 

 attempt to make a similar substitution in the case 

 of the determination of star places. The experi- 

 ment is a timely one, since astronomers are con- 

 fronted with the necessity for observing the places 

 of many stars, this necessity arising out of the 

 recent striking developments in the matter of star- 

 streaming. 



Proiaile masses of comets: Henry Norris Rus- 

 sell, Ph.D., professor of astronomy, Princeton 

 University. 

 The relationship of stellar motions to absolute mag- 

 nitudes: Walter S. Adams, A.M., Sc.D., assist- 



