ioo4 



Journal of Agricultural Research 



Vol. VI, No. 25 



expected if they occur in a given ratio to normal eggs can only be decided 

 by a comparison of the production of dwarf eggs with the normal-egg 

 production. 



The monthly distribution of normal-egg production has been investi- 

 gated thoroughly in the Maine Station flock by Pearl and Surface (19). 

 Their investigations cover the eight years preceding the beginning of the 

 present study. They summarized their data for the whole period by 

 obtaining the percentage of the total yearly egg production which occurred 

 during each month. This egg-production polygon may be used as a 

 basis for a rough comparison between the relative seasonal frequency of 

 dwarf and normal eggs. Figure 1 shows this egg-production polygon and 

 a similar polygon showing for the eight years of the present investigation 



HIIIHillUl 



Fig. i.— Diagram showing the percentage of the yearly total egg production (8-year average, 1899-1907) 

 and the percentage of the total dwarf-egg production (8-year average, 1908-1916) which occurred during 

 each month. Solid line= percentage of annual egg production. Dash line= percentage of annual dwarf- 

 egg production. 



the percentage of all of the dwarf eggs which were produced during each 

 month. The data are given in the last two lines of Table XXIII. It will 

 be noted that the two polygons do not begin or end with the same month. 

 The reason for this is that the first set of data was collected for September 

 and October after the birds were a year old, while, as already stated, dur- 

 ing the period covered by the second investigation the data from Sep- 

 tember 1 to September i represent more nearly the data on a single group 

 of birds. 



From the diagram it is seen, as would be expected on the theory of 

 chance, that during the months of heaviest normal-egg production more 

 dwarf .eggs are produced than at other seasons. Yet it is also seen that 

 the two curves are by no means parallel. The egg-production curve rises 



