98 MAINE AGRICULTURAL EXPERIMENT STATION. I9IO. 



P. E. ratio = -67449 y pq/n. 

 where p = percentage of males, q = percentage of females 

 (rrr iQG — p) , and 11 = the total number. 



Applying this formula to the data in Tables 7 and 8 we have 

 the following results : — 



Percentage of males amongst all hybrids 50.42 ±1.55 



Percentage of males amongst all pure Barred 



Rocks 48.75 =t: .91 



Percentage of males amongst all pure Cornish. . . 43.70 ± 2.88 

 Difference in proportion of males between hybrids 



and Barred Rocks 1.67 ±: 1.80 



Difference in proportion of males between hybrids 



and Cornish 6.72 ±: 3.27 



It thus appears that i 2-3 percent, more males are produced 

 in hybrid than in pure Barred Rock matings, and 6.72 percent 

 more than in pure Cornish matings. The probable errors are 

 of such magnitude, however, that it cannot be asserted that 

 these differences are significant. The data are of interest in 

 so far as their general trend is concerned, however, and will be 

 of value, in connection with further material to be collected in 

 the future, in helping to settle this particular phase of the prob- 

 lem of sex-determination. 



3. The chick mortality, both absolute and percentage, is sub- 

 stantially equal in the two sexes in the case of the hybrids. 



4. In the case of the pure bred chicks the percentage mor- 

 tality is distinctly higher for the males than for the females, in. 

 both breeds. No reason for this marked difference in the mor- 

 tality rate of the sexes in pure bred birds is apparent. Nor is 

 it clear why there is a difference between hybrid and pure bred 

 birds in this regard. It is idle to discuss the various specula- 

 tions regarding the possible cause of this relation which come 

 to one's mind until more ample data can be had. 



5. The mortality shown in Tables 7 and 8 is absolutely 

 high. These tables give in that respect an entirely wrong 

 impression of the general vigor and vitality of the chicks raised 

 in the spring of 1909. The reason why the mortality figures 

 are so high in these tables has little relation to the real quality 

 of the chicks themselves. The high mortality originates from 

 the results of one hatch. On April 21, 1909, a large hatch 

 (between 600 and 700 chicks) was brought off. These chicks 



