BROODINESS AND FECUNDITY IN FOWL 63 



The very large standard deviation in times broody suggests a most pro- 

 nounced variability in number of broody periods. The actual range is from 

 1 to 12. Since the modal class is broody but once, there can be l)ut little 

 further progress in reducing the mean number of broody periods within the 

 broody race. 



nie mean December rate is slightly higher tlian that for both broodies and 

 non-broodies combined, in section 1. The standard deviation in rate is of the 

 same magnitude as tliat in section 1. 



The coefficient of correlation between degree of broodiness and December 

 rate is actually less than its probable error, and since it is of very small 

 magnitude, tlie interpretation seems justified that December rate is indepen- 

 dent of degree of broodiness, and that the correlation in section 1 is false. 



■K Correlation heticeen the Presence of Broodiness and December Rate above 

 the Mean of Broodies and Non-broodies Combined — Pullet Year. 



The actual correlation between tlie presence of broodiness and higii rate 

 is of mucli importance to the breeder. Such a constant was calculated for 

 the 194^5 l)roody and non-broody birds by the method of Yule (loc. cit.). 



Coefficient of correlation -f-.I466 ± .0150 



Although the degree of correlation between the presence of broodiness and 

 high December rate is not large, there can lie no justification for any other 

 deduction than that the presence of broodiness is partially linked with high 

 December intensity. The elimination of the broody trait should result in 

 something of a reduction in December rate for tlie flock as a whole. 



A further consideration of this relationship in a flock iiigli in broodiness and 

 in a flock low in broodiness seems advisable. The 1916 flock showed 86.31 per 

 cent broody and is unimproved, at least for broodiness. The 1923 flock showed 

 27.35 per cent broody and may be classified as an improved flock. 



4. Correlation Between the Presence of Broodiness and December Rate above 

 the Mean of Broodies and Non-broodies Combined — Pullet Year (Unimproved 

 Flock 1916). 



In the total of 253 birds the following results were obtained: — 



