No. 590] FECUNDITY IN THE DOMESTIC FOWL 



fluctuations. In the first four years (1899-1900, 1900- 

 1901, 1901-1902, 1902-1903) of the old experiment the 

 birds were kept in 50-bird flocks. During the five years 

 following (i. e., to 1908-1909) they were kept in 50, 100, 

 and 150 bird flocks. Just precisely how much (or really 

 how little) difference the size of flock made in average egg 

 production has been fully and minutely analyzed bio- 

 metrically and published by Pearl and Surface 10 some six 

 years ago. It seems reasonable to suggest that before 

 indulging in fast and loose criticism on such a simple 

 point of fact as this it would become Professor Castle to 

 read the literature respecting the work he is attacking. 

 Since this material seems to have been forgotten it may 

 be well to repeat here that the results showed (Pearl and 

 Surface loc. cit, p. 115) that in general there was no sig- 

 nificant difference in winter production between 50, 100, 

 and 150 bird flocks. In later months of the laying year 

 differences appeared but only in the last month of the win- 

 ter period (February) was there any significant excess of 

 even 50-bird flocks over the others. Furthermore, besides 

 the material which has already been published regarding 

 the possible influence of environmental factors on the re- 

 sults of these experiments, I have carried out a number of 

 special investigations on different phases of this general 

 question which have not yet been published. For example, 

 I have minutely analyzed the data regarding date of hatch- 

 ing to see whether that might not enter as a significant 

 factor in the interpretation of the results. The data on 

 this question are being prepared for publication now, but 

 it may be said in advance that the results show that date 

 of hatching can not possibly have had anything to do with 

 the rise in average flock production which has occurred 

 between 1908 and 1915. 



