144 MAINE AGRICULTURAL EXPERIMENT STATION. IQIl, 



An examination of adult mortality records leads to the same 

 conclusion as the fecundity records. The percentage mortality 

 amongst the adult daughters from out-cross matings was 11.3 

 per cent. Among the daughters from narrow matings in house 

 No. I, the mortality was 10.8 per cent. For the daughters of 

 all narrow matings the mortality rate was the same, viz. 10.8. 

 Thus it is clear that as measured by this index the out-crossed 

 stock was no more vigorous than the narrow bred. 



It may further be said that not only was there no difference 

 in the first generation between the offspring of out-cross and 

 narrow matings, but further there was no difference in the 

 progeny in subsequent generations. Putting in "new blood" did 

 not improve or rejuvenate the stock. One must then conclude 

 either (a) that the stocjc was so hopelessly and completely de- 

 generate as to be past any benefit from infusion of new "blood," 

 or (b) that the stock was not deteriorated in respect of consti- 

 tutional vigor or vitality and that therefore it could not be ex- 

 pected that out-crossing would have any rejuvenating effect. 

 The first conclusion certainly cannot be deemed the correct one 

 in view of the evidence presented in this bulletin in respect to 

 mortality, egg production, etc. The stock has never been in the 

 condition of excessively low constitutional vigor which would 

 be demanded by such a conclusion. 



It would then appear that there is no evidence that the 

 amount of inbreeding practiced during the mass selection ex- 

 periment had any unfavorable influence on either the egg pro- 

 duction or the general vitality of the stock. 



PART III. 



Ne;w Plan oe Breeding for Egg Production. 



At the end of the period from 1898 to 1907 during which 

 the mass selection experiment had been carried on it seemed 

 advisable to inaugurate a change in the plan of investigation. 

 Considering the results obtained, and the fact that a large 

 amount of statistical data had been accumulated and was avail- 

 able for analysis, it appeared unlikely that further continuation 

 of mass selection would yield results of sufficient value to war- 

 rant carrying on the work. The ultimate object of the work at 

 the Maine Station in this field was, and is, to get at the under- 



