384 MAiNi: AGRicutTURAL i;xpe;rime;nt station. 1912. 



ough biometrical and physiological study of egg production in 

 fowls howed beyond question that winter production was the 

 best practicable index or measure of a fowl's innate or constitu- 

 tional capacity in respect of fecundity. The reasons for this 

 conclusion have been set forth in this and former papers from 

 the laboratory and need not be repeated in extenso here. The 

 most significant of them is that the differences in observed pro- 

 duction between individuals of different innate fecundity capaci- 

 ties are relatively greater in respect of winter productions than 

 of any other time unit that can practically be employed in the 

 measuring of this character. To suppose, however, that the re- 

 sults set forth in this paper depend for their existence upon the 

 use of this particular time period of production as a measure 

 of fecundity has no warrant in fact. Precisely the same results 

 (in principle) would be obtained if yearly production records 

 were used in the analysis. During the whole of this work com- 

 plete yearly records have been kept and have been studied. They 

 show in every essential particular the same kind of results as 

 those of this paper. There are objections to the use of the year 

 as a unit of measure, however, which may not be obvious to one 

 inexperienced in these matters. In the first place, it is very 

 much more difficult to keep large flocks of hens in normal, and 

 healthy physiological condition over a whole year period than 

 over a shorter period. Again the risk of an accident (say the 

 use of bad feed or something of the kind) occurring and up- 

 setting the birds physiologically, and coincidently rendering their 

 fecundity records abnormal and in greater or less degree use- 

 less, is increased just in proportion as the time unit is increased. 

 Further the year period includes as a too dominant feature, the 

 spring egg production. The production during the months of 

 March, April and May is practically worthless (and has long 

 been so recognized by experienced poultrymen) as an index or 

 measure of the true, innate or constitutional fecundity capacity 

 of the individual. During these months (in northern latitudes) 

 all hens which are not diseased, malformed, infantile or senile, 

 lay anywhere from 'well' to 'very well.' There is relatively lit- 

 tle difference between the most and the least fecund at this 

 season. This period is therefore worthless as a measure of 

 fecundity, and its inclusion in any longer period makes that by 

 so much the less valuable as a measure. 



