542 



SCIENCE 



[N. S. Vol. XLVII. No. 1222 



Physically, mechanically and stylistically 

 Professor Skinner's College Algebra is a tidy 

 piece of work. It is up-to-date in its inclu- 

 sions, exclusions and emphases. Its early use 

 of geometric representation is happy. The no- 

 tion of function occupies a dominant place in 

 the entire perspective. In the definition of this 

 potion (p. 49) the meaning of the term 

 " known " may lead to interesting dialectic, 

 especially if the function be implicit. Five 

 convenient tables are inserted at the end of the 

 volume. 



Professor Bowling's " Projective Geometry " 

 is a handsome introduction to the most ex- 

 quisitely beautiful of mathematical subjects. 

 The treatment, which is in the manner of 

 Reye's classic " Geometric der Lage," is syn- 

 thetic as distinguished from algebraic, and 

 presupposes no knowledge beyond ordinary 

 elementary geometry and a very little trigo- 

 nometry. It does not aim at the rigor of the 

 postulational method, but is preliminary 

 thereto and admirably qualifies the reader to 

 appreciate the nature and the value of that 

 method. 



In his " Elliptic Integrals " Professor Han- 

 cock has compressed a large aanount of matter 

 into a small compass. If the work be too com- 

 pact for most of those who would like to read 

 it, the fault is not that of the author but rather 

 that of the editors who desired him to write a 

 work which "shall relate almost entirely to 

 the three well-known elliptic integrals, with 

 tables and examples showing practical applica- 

 tions, and which shall fill about one hundred 

 ■octavo pages." This asdgned task has been 

 done faithfully, and the reader will thank the 

 author for his full citation of the literature of 

 the general subject. 



0. J. Keyser 



Columbia IjNrvEEsiTY 



SPECIAL ARTICLES 



INHERITANCE OF WINTER EGG PRODUCTION 



PRELIMINARY REPORT 



A. Progeny of a Cornish Male. — A Cornish 

 male was mated simultaneously to several (5) 

 Ehode Island Eed hens of high fecundity 



families with a mean winter production of 

 52.5 eggs and to several Cornish females. The 

 latter are poor winter layers with a mean of 

 8.47 eggs. There were 33 pullets from the 

 Cornish and Rhode Island Red cross with a 

 mean winter production of 49.2 eggs, the range 

 being 21-86. 



The offspring of this male with pure Cornish 

 females were 11 in number and with the ex- 

 ception of a single individual were poor winter 

 layers, the average of all being 11.6 eggs. 



The result from the Cornish male and 

 Rhode Island Red female cross is diamet- 

 rically opposed to that obtained by Pearl from 

 Cornish males (of the same strain that I used) 

 bred to Barred Plymouth Rock females which 

 are good winter layers. The offspring of this 

 ■cross gave a mean winter production of 16.7 

 eggs. The reciprocal cross, viz.. Barred Rock 

 males and Cornish females, gave an average 

 tvinter production of 30.7. We have no data 

 at present from the corresponding cross with 

 Rhode Island Reds. It is clear from the re- 

 sults of my experiment that high-producing 

 hens are able to transmit this ability directly 

 to her daughters, that is, high fecundity in 

 Rhode Island Reds is not sex-linked. 



B. A Theory of the Inheritance of Winter 

 Egg Production Alternative to Pearl's. — ^It 

 has been foimd that the observed ratios in 

 which high and mediocre producers occur, 

 both in Pearl's data on Barred Plymouth 

 Rocks and my own with a large series of Rhode 

 Island Reds, can be explained satisfactorily 

 by assuming that high egg production de- 

 pends upon two factors that follow the usual 

 dihybrid Mendelian scheme. One factor 

 alone, in either simples or duplex condition, 

 is assumed to give mediocre production. This 

 theory encounters only one difficulty, viz., in 

 a few instances there is a deficiency in the 

 expected numbers of high producers, a result 

 easily explicable with a physiological character 

 such as egg production. Pearl's theory, how- 

 ever, encounters the reverse difficulty, i. e., 

 high producers appear where none are expected. 

 This difficulty is explained by Pearl on the 

 very reasonable assiunption that it is due to 

 an overlapping of phaenotypes. 



