1918] ANIMAL PRODUCTION. 171 



clence that the female is a suppressed hermaphrodite, because the secretion of 

 the ovary clearly controls their development. On the other hand, It is clearly 

 proved that the female is a suppressed pseudohermaphrodite. On the whole, 

 the relation between the gonads and the secondary sex characters appears to be 

 specific and not general. 



The three most important results are as follows: (1) If the ovary of a 

 domestic bird be removed completely, many of the secondary sex characters of 

 the male appear (and always of the male of the same race). Some individuals 

 become nearly complete replicas of the male, others imperfect imitations of the 

 male. (2) If the testes be removed, the majority of the secondary sex char- 

 acters of the male develop, though a few may remain in an Infantile condition. 

 (3) Castrated dral^es lose the power of developing the summer plumage. 



Contribution to the history of the development of the exterior attributes 

 of the male sex in female birds, O. Lakcher {Rec. Med. Vet., 91 (,1916), No. 

 11-12, pp. 173-183).— This is a historical summary of the literature pertaining 

 to this subject, including an extensive bibliography. 



Some observations on the origin of melanin pigment in feather germs 

 from the Plymouth Hock and Brown Leghorn fowls, R. M. Strong and 

 Katheeine Knowlton (Anat. Rec, 13 {19111), No. 2, pp. 97-108, figs. 6).— A 

 study was made of the melanin pigment in feather germs pulled from the back, 

 breast, neck, and wings of adult Plymouth Rock and Brown Leghorn male and 

 female fowls. 



Examination of sections cut from these feather germs showed that melanin 

 pigment granules occur occasionally In the so-called cylinder and inner-sheath 

 cells. Further evidence was obtained that the melanin pigment of feathers 

 is epidermal in origin. Melanophores were found in the dermal pulp at the 

 proximal end of feather germs. Some of t' ese pulp melanophores have proc- 

 esses which are usually relatively short, but they do not appear to distribute 

 pigment to other cells, and they have no part in the histogenesis of the feather 

 or its pigment. 



Inter-periodic correlation in the egg production of the domestic fowl, J. A. 

 HARfiis, A. F. Blakeslee, and W. F. Kirkpatrick {Proc. Nat. Acad. Sci., 3 

 {1917), No. 9, pp. 565-569, figs. 2).— This investigation deals with the correla- 

 tions between the egg production of various periods in White Leghorn fowls. 



The coefficients of correlation between the production of single months and 

 the production of the remaining 11 months of the year range, in the cases 

 observed, from 0.29.5 to 0.567 in the several months (November-October) of 

 1913-14 and from 0.24 to 0.567 in 1914-15. For purposes of prediction the 

 correlation coefficients may be thrown into the form of linear regression equa- 

 tions, which have been found to give reasonably good fits to the empirical means 

 for the annual egg records of birds laying various numbers of eggs in the indi- 

 vidual months. The slope of the lines when plotted shows there is an increase 

 of from 2.6 to 5 eggs in mean annual production associated with a variation 

 of one egg in monthly record. Since in practical selection groups of birds 

 differing by far more than a single egg may be recognized, the difference in 

 annual production secured by selecting in any mouth may be of very practical 

 importance, amounting to from 30 to 60 eggs per year. 



Coefficients are also given showing the correlation between the annual total 

 and the deviation of the monthly record from the value which it should have 

 if variation in monthly production were directly proportional to variation in 

 the annual production. Sets of correlations, 110 coefficients in all, have been 

 worked out for the production of five of the individual months and the pro- 

 duction of each of the other months of the contest year (November-October). 

 40111°— 18— No. 2 6 



