BRISTLE INHERITANCE IN DROSOPHILA 97 



The similarity with much recent work that has given more 

 or less positive evidence of multiple and duplicate factors, per- 

 suades the author that the hypothesis of accessory factors is 

 probably the best one for the facts. 



The following hypothesis is adopted upon which to base 

 further w^ork: the extra bristles in Drosophila ampelophila are 

 due to the absence of one main restricting factor, and their 

 number is also influenced by accessory restricting factors, which, 

 in the absence of the main one, produce flies with reduced num- 

 bers of extra bristles. 



October, 1914. 



LITERATURE CITED 



Balls, W. L. 1907 Mendelian studies of Egyptian cotton. Jour. Agric. Sci., 



vol. 2, p. 365. 

 BiPPEN, R. H. 1905 Mendel's law of inheritance and wheat breeding. Jour. 



Agric. Sci., vol. 1, p. 4. 

 Castle, W. E. 1914 Size inheritance and the pure line theory. Zt. f. ind. 



Abs. u. Verb., Bd. 12, s. 233. 

 Castle, W. E., and Phillips, J. C. 1914 Piebald rats and selection. An 



experimental test of the effectiveness of selection and of gametic 



purity in Mendelian crosses. Pub. Carnegie Inst, of Washington, No. 



195. 

 Davenport, C. B. 1913 Heredity of skin-color in negro-white crosses. Pub. 



Carnegie Inst, of Washington, No. 188. 

 East, E. M., and Hayes, H. K. 1911 Inheritance in maize. Conn. Agric. 



Exp. Sta. Bull. No. 167. 

 Hayes, H. K. 1914 The inheritance of certain quantitative characters in tobacco. 



Zt. f. indukt. Abstammungs- u. Vererbungslehre, Bd. 10, s. 115. 

 HoGE, M. A. 1915 The influence of temperature on the development of a 



Mendelian character. Jour. Exp. Zool., vol. 18, no. 2, p. 241. 

 Ikeno, S. 1914 Studien uber die Bastarde von Paprika (Capsicum annum). 



Zt. f. indukt. Abstammungs- u. Vererbungslehre, Bd. 10, s. 99. 

 Leake, H. M. 1911 Studies in Indian cotton. Jour. Genet., vol. 1, p. 205. 

 LoTSY, J. P. 1913 Hybrides entre especes d' Antirrhinum. Compt. rend. 4^ 



Conf. Internat. de Genetique, p. 416. 

 MacDowell, E. C. 1914 a Multiple factors in Mendelian inheritance. Jour. 



Exp. Zool., vol. 16, no. 2, p. 177. 



1914 b Size inheritance in rabbits. With a prefatory note and appen- 

 dix by W. E. Castle. Pub. Carnegie Inst. Washington, No. 196. 

 Nilsson-Ehle, H. 1909 Kreuzungsuntersuchungen an Hafer vmd Weizen. 



Lunds Universitets Arsskrift, N. F. Afd. 2, Bd. 5, Nr. 2. 

 Pearl, R. 1912 The mode of inheritance of fecundity in the domestic fowl. 



Jour. Exp. Zool., vol. 13, no. 2, p. 153. 



