124 MAINE AGRICULTURAL EXPERIMENT STATION. IQH. 



kept constant and the factor continues to act, is, of course, one 

 reason why it is so exceedingly difficult to get really critical 

 evidence on the question of the inheritance of acquired charac- 

 ters. 



In addition to the cumulatively adverse effect of environment 

 as an explanation of the results of the earlier work at this 

 Station another possible interpretation which is essentially 

 physiological in its nature occurs to one. It is that any favor- 

 able progress in the way of increasing egg production by the 

 selection was offset in the experiment by the weakening and 

 debilitating effect upon the birds of the inbreeding which it 

 might be contended was practiced during the experiment (see 

 p.. 115 above for facts on this point). 



Another suggestion which has been made is that while there 

 was no progressive increase in egg production following the 

 mass selection this has no bearing on the question of the effect- 

 iveness of the selection of minute fluctuating variations because 

 the character fecundity or egg productiveness is not inherited 

 in the domestic fowl at all. 



It is the purpose of this section to discuss these various sug- 

 gestions one by one, presenting evidence which it is hoped will 

 help to throw light on the subject. The evidence on the last 

 mentioned criticism (that having to do with the non-inherit- 

 ance of fecundity) will be presented in Part IV. 



ARTIFICIAL HATCHING AND REARING. 



The practical management of poultry naturally and obvious- 

 ly- divides itself into three great divisions, namely (i) housing, 

 (2) feeding, (3) incubating and rearing the chicks to replenish 

 the flock. In considering the possibility that in the experi- 

 ments under discussion some adverse factor in the environment 

 (which broadly-speaking in the case of poultry on an intensive 

 plant means the management) masked or concealed a favorable 

 effect of the selection, it will be well to deal with each of these 

 three divisions of management separately. 



The methods of housing or feeding the stock practiced dur- 

 ing the period of the selection experiment cannot, I think, rea- 

 sonably be held to have had any adverse effect upon, or to 

 have masked or covered up, any innate, inherited improvement 

 in egg production conceived to have resulted from the selec- 



