BREEDING POULTRY FOR EGG PRODUCTION, 121 

 PART II. 



.Critical Conside^ration of Possibli: Inte:rpre;tations of 

 Earlier Work. 



The critical interpretation of the results of the mass selection 

 experiment described in the preceding section is by no means a 

 simple matter. As to the bare facts as such there can be no 

 question, but how shall they be interpreted? What really do 

 they mean? 



There are two principal general interpretations or explana- 

 tions which may conceivably be given for the selection experi- 

 ments at the Maine Station between 1898 and 1907 turning 

 out in the way which they did. On the one hand it may be said 

 that the results indicate that the general theory of the effective- 

 ness of selection, or even more broadly the theory of breeding, 

 which was at the foundation of this experiment, is, in greater 

 or less degree, inadequate or incorrect. That is to say, the ex- 

 periment may be interpreted, as it has been by the writer, as 

 showing that it is doubtful whether the picking out by selection 

 of minute favorable variations has in reality any cumulative or 

 additive effect, so far as concerns the hereditary or germinal 

 constitution of an animal, at least with reference to the char- 

 acter fecundity or egg production in fowls. 



Before reaching such a conclusion, however, one must con- 

 sider on the other hand, alternative interpretations and see 

 whether the facts cannot be equally well or better explained in 

 some other way. A number of such alternative explanations 

 may be thought of. Nearly all of these explanations which 

 suggest themselves fall into one category. This category is, to 

 characterize it in a word, the effect of environment. In general 

 tenriS this explanation of the results obtained would run some- 

 thing like this : that in reality the selection for increased egg 

 production practiced during the years 1898- 1907 was inherently 

 or potentially effective, but that during this same period of 

 years one or another or a combination of environmental cir- 

 cumstances became progressively worse, so that the gain which 

 may be supposed to have been made each year as a result of 

 the selection was masked or hidden by the untoward effect of 

 the environment which prevented- the hens from laying up to 

 what was their true or innate capacity in the way of fecundity. 



