INHERITANCE OF FECUNDITY 183 



well developed pullets can be used in the work, since any other 

 sort could not be depended upon to give reliable normal results as 

 to fecundity. This means that, under the prevailing climatic 

 conditions here, only pullets hatched between a rather narrow 

 range of dates (April 1 to June 1) can be used in the fecundity. 

 Those hatched at other seasons will not give normal results. 



Altogether it will be seen that the character fecundity in fowls 

 is not "one which lends itself readily to treatment in large masses 

 of figures, desirable as such might theoretically be. The case is 

 very different from the study of the inheritance of plumage colors 

 in poultry, for example, where both sexes are available for record 

 and the records may be made while the chicks are relatively 

 young (or in some cases even unhatched) and before they have 

 time to die. If all students of the inheritance of pigmentation in 

 poultry had been obliged to keep, house, and feed every bird 

 which was to furnish any record whatever, until approximately 

 one and a half years after hatching, and could have got records 

 even then only from one sex (both of which conditions obtain 

 in the study of fecundity), it is plain that their recorded numbers 

 would have fallen very far below those which they have actually, 

 and most fortunately for the good of biology, been able to obtain. 



The foregoing remarks are not in any sense intended as an 

 apologia for the statistical portion of this paper, because in the 

 opinion of the writer, who is thoroughly acquainted with the 

 practical difficulties which beset the study of inheritance of fecun- 

 dity, no apology is needed. The data here presented are about as 

 extensive as it is practically possible to obtain in an interval 

 of time and with an experimental equipment equal to what has 

 been available in the present investigation. It is hoped, however, 

 that what has been said ma}^ help the reader, who may not be prac- 

 tically familiar with the rearing and trap-nesting of large numbers 

 of fowls, to understand the reason why more extensive data are not 

 forthcoming in this paper. In every case where the number of 

 birds to a family was too small to warrant any conclusion this 

 fact is particularly noted. The data for these small families are 

 not suppressed, however, but are in most instances separately 

 tabulated. 



