ANIMAL PEODUCTION. 375 



The arithmetic of the product moment method of calculating the coefficient 

 of correlation, J. A. Harris (Amci: Nat., J,.i {1910), No. 527, pp. 693-699).— A 

 short method is described which consists in taking for y arrays of variates O 

 instead of the grade thought to be nearest the mean origin. In this way the 

 total for the array may be obtained by adding the products of the frequencies 

 by their grades. By multiplying up by the grade of a? character 8(x'y') is then 

 at once obtained. 



Inheritance of color and of supernumerary mammae in guinea pigs, with a 

 note on the occurrence of a dwarf form, Igerna B. J. Sollas (Rpts, to Evolu- 

 tion Com. Roy. Soc. [London], 1909, No. 5, pp. 51-79, pi. 1, figs. 2; abs. in Ztschr. 

 InduktivG Ahstam. a. YercrhungsWire, 4 (1910), No. 2, p. 155). — A report of 5 

 years' experhiieuts with guinea pigs, in which the characters studied were pig- 

 mentation, dwarfness, and supernumerary mammfe. 



Albinism was found to be recessive to the fully colored forms. The other 

 color factors were G, ticking of the hairs ; B, black pigment in the eye and skin ; 

 R, red pigment in the hair, and red and chocolate pigment in the skin and eye; 

 and Ch, chocolate pigment in the hair, skin, and eye. These colored forms fall 

 into 2 series, a dark-eyed series and a ruby-eyed one, according as the factor for 

 black pigment is present or absent. Each of these forms may exist in a dilute 

 condition, and such dilute foi'ms behave as recessive to the corresponding form 

 with intense pigmentation. 



A peculiar dwarf form appeared wliich was remarkable in the shortness of the 

 body and limbs and the unusual form of the head. No oflspi-ing were obtained. 

 The proportions in the families where they occurred, 74 normals to 25 dwarfs, 

 point to the condition as being recessive. Four-fifths of the dwarfs were males. 



Supernumerary mammae were present in both sexes. More than one addi- 

 tional pair were never observed, and in many cases an additional mamma was 

 present on one side only. The heredity of this character resembles that of the 

 extra toe in guinea p'igs and poultry, in apparently showing neither dominance 

 nor recession. Thus, normal offspring of abnormal parents may give some 

 abormal young. 



Sex-limited inheritance, P. B. Hadley (Science, n. ser., 32 (1910), No. 831, 

 p. 797). — This is a note concerning numerous crosses of poultry made at the 

 Rhode Island Station in 1892, which illustrates sex-limited inheritance. 



In the Indian Game-Plymouth Rock crosses the cockerels were between In- 

 dian Game and Plymouth Rock in shape. The combs resembled those of the 

 Indian Games and the plumage that of the Plymouth Rocks. The pullets were 

 black and more like the Indian Games in shape. 



Investigations on the cause of hair whorl in domesticated animals, with 

 special reference to the forehead " star " and its practical significance for 

 judging live stock, E. Bosch (Untersuchungen iiber die Ursache der Haarwir- 

 helhihliing hel den Hausticren mit hesonderer Beriicksichtigung des Gcsiclits- 

 wirbcls und dessen praktische Bedeutung fiir Beurteilung, Leistiing und Zucht 

 der Haustiere. Inaug Diss., Univ. Bern, 1910, pp. 55, figs. //; Jahrb. Wiss. u. 

 Prakt. TierzucM, 5 (1910), pp. 9-'i-lI,0, figs //.—The prevalence of many 

 maxims among breeders concerning the hair whorls as a sign of a good breeding 

 animal has led the author to study minutely the anatomy and physiology of 

 the hair and surrounding tissues and the development of the hair and hair 

 follicles in the embryo. 



As a result the author finds that the position and size of the whorl on the 

 forehead is dependent upon the movements of the ears, eyes, nose, and lips 

 and the texture and thickness of the skin. He has illustrated the action of 

 the different muscles by stretching a sheet of rubber perforated with pins 



