1004 



SCIENCE 



[N. S. Vol. XXIX. No. 756 



biology of aquatic plants, by Professor Wylie; 

 (3) the nature of plants, by Professor Wylie. 

 Opportunities are afforded, also, for research 

 work in botany under the direction of the two 

 professors named. In the second term, work 

 is offered in field ecology and plant taxonomy 

 by Professor Shimek. Courses in geology, 

 zoology and nature study also are offered by 

 competent instructors. The management of 

 this summer-school work is in charge of the 

 director of university extension at Iowa City. 

 Charles E. Bessey 

 The Univeksity op Nebeaska 



SPECIAL ARTICLES 



SEX AND ITS RELATION TO THE BARRING FACTOR 

 IN POULTRY 



W. J. Spillman' has suggested that the bar- 

 ring factor and sex in poultry are correlated 

 in such a way that the female is always hetero- 

 zygous in respect to sex and also barring when 

 present. The male, on the other hand, is 

 always homozygous in respect to sex and may 

 be either homozygous or heterozygous in re- 

 spect to barring. I have recently performed 

 the following experiments, which bear directly 

 on this point and confirm his theoretical de- 

 ductions. 



Experiment 1. — A Buff Rock male (non- 

 barred) bred to Barred Bock females give, in 

 F^, barred males and non-barred (blacks or 

 buff) females. 



Experimeni 2. — A Barred Rock male bred 

 to Buff Rock females (non-barred) or a 

 Rhode Island Red female (non-barred) gives 

 in F^, all barred birds in both sexes. 



Experiment 3. — A Buff Rock male bred to F^ 

 females (non-barred) from experiment 1 gives, 

 in F^ chicks which do not show the down 

 pattern characteristic of chicks from barred 

 parents, thus indicating an entire absence of 

 barring in F^. 



These experiments may be formulated, thus: 

 Using B = barring factor, h = its absence ; 

 F = the female sex factor, f = its absence 

 or the male sex factor. Assume that B and 

 F can not occur in the same gamete (Spill- 

 man) . Then, 



Mm. Nat., Vol. XLII., No. 50, 1908. 



Experiment 1 becomes If ■ hf "X^ Bf ■ hF ^ 

 Bf-hf+hf-hF. 



Experiment 2 becomes Bf ■ BfXM-'bF = 

 Bf-hf'+Bf-hF. 



Experiment 3 becomes hf ■ hf XM ' ^F = 

 If ■ hf + lf-lF. 



Other crosses giving similar results are: 



Experiment 4. — A White Rock male (carry- 

 ing barring as a cryptomere) mated with 

 Brown Leghorn females gives in F^ both sexes 

 barred. 



Experim,ent 5. — The reciprocal cross, viz., 

 a Brown Leghorn male mated with White 

 Rock females gives black chicks and chicks 

 having a down pattern like that of Barred 

 Rock chicks. These chicks, however, are yet 

 too young to enable a determination of their 

 sex. 



Experiment 6. — A White Rock male (carry- 

 ing barring) bred to Buff Rock females gives, 

 in F^, both sexes barred. 



Experiment 7. — From the reciprocal cross I 

 have only two birds as yet, both barred males. 



Experiment 8. — One of the F^ barred males 

 from experiment 7 mated with a Buff Rock 

 female gives, in F^ barred and non-barred 

 chicks, which are still too young to permit of 

 their sex being determined. 



While my results appear to confirm Spill- 

 man's suggestion, I wish to point out that 

 experiment 3, rather than exiseriment 2, 4, 6 

 or 8, furnishes us the true test of his sugges- 

 tion, for the reason that the presence of the 

 F factor may simply prevent the B factor 

 from becoming visible under certain condi- 

 tions. In some experiments, at any rate, I 

 find that the presence of the F factor operates 

 to modify barring, making it appear obscure 

 and blurred as compared with males from the 

 same parents. On the other hand, we may 

 refer this obscuring of barring to some other 

 cause, perhaps the heterozygous nature of the 

 female. 



The details of these experiments are reserved 

 for a later paper. 



H. D. GOODALE 



Since the above note went to Science some 

 F„ chicks in experiment 3, have reached the 



