262 MAINE AGRICUVrURAI, EXPERIMENT STATION. IQI2. 



acters do in Mendelian crossings. As pioneer work in this 

 field stand the brilHant experiments of Doncaster and Raynor 

 with Abraxas, those of Bateson and Punnett with the silky 

 fowl, and those of Miss Durham on canaries.^ 



A'lore recently sex-limited inheritance (in which sex behaves 

 as a Mendelian character) has been further studied in fowls 

 by Goodale, Hagedoorn, Sturtevant and others." 



The same type of inheritance has been shown by A'lorgan^ 

 to hold for a number of characters in the pomace fly, Droso- 

 phila. 



The evidence, now considerable in amount, from both the cy- 

 tological and experimental lines of investigation, indicates clear- 

 ly that sex determination is not, as it was long supposed to be, 

 primarily an epigenetic phenomenon. Rather does it appear 

 chat the sex of the individual, into which a particular pair of 

 united germ cells will develop, is definitely and unalterably 

 fixed in the hereditary constitution of these germ cells them- 

 selves. 



In view of these well established conclusions the facts 

 regarding the distribution of sex in cases of multiple gestation 

 take on a peculiar interest. It has long been a well known 

 statistical fact that the sex ratios of offspring resulting from 

 multiple gestation in animals normally uniparous present dis- 

 tinct deviations from the normal. Thus it has recently been 

 shown by Nichols,^ after careful analysis of the available sta- 



^References to this earlier work are given in Bateson, W., Mendelian 

 Principles of Heredity, Cambridge, 1909, pp. 174-188. 



^Goodale, H. D. Sex and its Relation to the Barring Factor in Poul- 

 try. Science, N. S. Vol. 29, No. 756, pp. 1104, 1105, 1909. 



Hagedoorn, A. L., Mendelian Inheritance of Sex. Roux's Archiv. Bd. 

 28, pp. 1-34. 

 19C9. 



Pear], R. and Surface, F. M. On the Inheritance of the Barred Color 

 Pattern in Poultry. Roux's Archiv. Bd. 30. pp. 45-61, 1910. 



■ • Studies on Hybrid Poultry. Rept. Maine 



Experiment Station, 1910, pp. 84-116. 



Further data regarding the Inheritance of 



the Barred Color Pattern. Science, N. S. Vol. 32, pp. 870-874, 1910. 



'Morgan, T. H. Sex Limited Inheritance in Drosophila. Science, 

 N. S. Vol. 2,7, 1910. 



An Attempt to Analyze the Constitution of the Chromosomes on the 

 Basis of Sex-Limited Inheritance in Drosophila. Jour. Exper. Z06I. 

 Vol. II, 1911. Also a number of other papers on this subject. 



'Nichols, J. B. The Numerical Proportions of the Sexes at Birth. 

 Mem. Amer. Anthropol. Assoc. Vol. I, Part 4, pp. 249-300, 1907. 



