126 MAINE AGRICULTURAL EXPERIMENT STATION. I909. 



widely varying pens the deviation is to be explained as the 

 result of too few hens on which to base a fair average. Con- 

 sequently there is an overwhelming influence on the average 

 of the performance of one exceptionally good or one excep- 

 tionally poor pullet. Thus in the case of pen 13 (1908) the 

 cockerel average of 9.7 per cent, of infertile eggs is based on 

 the performance of only three birds, and one of these (No. 

 734) made (for that year) the very exceptional record of only 



4 per cent, infertile eggs. Similarly in pen 17 the very poor 

 cockerel record of 34.8 per cent, infertile eggs is largely due to 

 the influence of one particular pullet (No. 743) 82 per cent, of 

 whose eggs were infertile. When an average is based upon but 



5 cases as in pen No. 17 and one of these deviates so widely 

 from the others as does the record of 743 it is not remarkable 

 that the general average is affected. 



The pen averages do not run quite so smoothly in 1909 as 

 in 1908. This is in part to be acounted for by the fact that in 

 1908 only young birds (pullets and cockerels) are included in 

 the table, whereas in 1909 pens 11-14 inclusive were made up 

 of birds hatched in 1907. In general the indications from both 

 tables are that the male birds used in these two years were a 

 fairly even lot so far as breeding ability is concerned. 



3. The effect of the closed, heated house No. i in reducing 

 the fertility of eggs is brought out in two ways by these tables. 

 It is clearly shown in the data of Table VII alone. Breeding 

 pens 20 and 21 (1908) were in the curtain front house No. 2. 

 Breeding pens 5 to 19 inclusive of that same year were in house 

 No. I. The difference in the average infertility of the eggs 

 from the two houses is shown in the following figures. 



Average from House No. i (pens 5-19 inclusive) =23.1%. 



Average from House No. 2 (pens 20 and 21) = 14.8%. 



The bad effect of house No. i on fertility is, of course, 

 further shown by comparison of the last columns in Tables VII 

 and VIII, the first 15 entries in this column in Table VII repre- 

 senting data from house No. i and Table VIII data from house 

 No. 2. 



It is noteworthy that the average fertility shown by the two 

 breeding pens which were in the curtain front house No. 2 in 

 1908 (pens 20 and 21) is very nearly the same as the average 

 fertility from all pens in the same house in 1909 (14.8% and 



