182 RAYMOND PEARL 



From these data the following points appear to be clearly 

 estabhshed : 



1. The egg production of the treated birds and the untreated 

 controls was entirely normal in respect of its seasonal distribu- 

 tion, as well as in regard to its amount. 



2. There has been no significant difference in the egg i:)rodiic- 

 tion of the treated birds and their untreated control sisters, 

 either in the total average number of eggs produced per bird, nor 

 in the seasonal distribution of this production. Taking the 

 whole untreated flock, the mean production per bird in the 

 15 months was 184.74 eggs, while the mean production for the 

 treated birds was 183.97, making a difference of 0.77 egg in 

 favor of the untreated. Taking the 'Special Control' mean of 

 180.80 eggs there is a difference between this and the treated 

 of 3.17 eggs in favor of the treated. Obviously the only con- 

 clusion which can be drawn from these insignificant differences 

 is that the inhalation treatment has not affected the egg produc- 

 tion of the birds, either favorably or adversely. 



3. During the months of July, 1915, to October, 1915, inclu- 

 sive the mean production of the treated birds falls below that of 

 their control sisters. The difference between the two cur\^es in 

 this region is no greater than may at any time occur between 

 two similarly managed groups of sisters, according to the writer's 

 experience with egg records. There appears to be no reason 

 to attach any significance to this dip of the treated below the 

 control curve. Taking the whole period covered by the diagram 

 it is clear that the two curves wind about one another, now one, 

 now the other being uppermost, just as curves for two random 

 samples of the same material would be expected to do. 



V. SUMMARY 



A summary of the numerical data regarding the effect of the 

 treatment upon the treated birds themselves is given in table 

 6. In this table the superior result is printed in bold faced 

 type. In the last column of each table a plus sign denotes that, 

 ^^dth reference to the particular character discussed, the alco- 



