ANIMAL PRODUCTION, 373 



of the series on the pliysiolo^'y <if rcprcpiliK-tiou in tlu" (Inmi'stic fowl (10. S. It., 

 21, p. 271). 



Experiments nre loportod in wlii>-h " i-c.^istcrcd pulli'ls" ( (liui.t,'lilors of 200-et;R 

 bens) are compared with their motliers and with unret;islered pullets in respect to 

 efijr production wlien j^iven tlie same treatment as to housinj;. feeding, and care. 

 Two hundred and titty liarred Plymouth Kock pullets, each the (hiu.^hter of a 

 200-egg heu, were divided into five equal flocks. All the birds were trap nested 

 from November 1, 1907, to July 1, 1908. The registered mother hens averaged to 

 lay 58^S eggs per bird between November 1 and March 1, or a iiercentage produc- 

 tion of 40.5. .The daughters averaged 15.29 eggs per bird, a percentage produc- 

 tion of 12.7. The egg production of the registered mother hens in the S]iring 

 months, from March 1 to July 1, averaged 59.1.'} eggs, a percentage production of 

 04.4. The daughters averaged 40.(51 eggs, a percentage production of ,59.7. " There 

 is no reason whatever to suppose that these averages would have been any 

 nearer together if records for the daughters had been taken for the whole year." 



Constants of variation and correlation measuring the degree of inheritance 

 were determined. The constants of variation were found to be as follows: The 

 standiird deviation of variation in egg production of the mothers when un- 

 weighted in winter was 14.00±1.2, in spring 7.7.3±0.00; of the mothers when 

 Aveighted w-ith their fecundity in wnnter ]4.93±0.51, in spring 8.41±0.3, in total 

 production 12.09±0.45; of the daughters in winter l(i.l±0.55, in spring 1S.1± 

 0.04, in total production 2e.3S±0.94. The coefficient of variation in egg produc- 

 tion of the unweighted mothers in winter was 25.2±2.29, in spring 13.07±1.13; 

 when weighted with their fecundity in winter 20.57±0.97, In spring 13.8±0.49, 

 in total production 9.32±0.33 ; of the daughters in winter 101.14±0.44, in spring 

 38.eG±1.54, in total production 35.43±1.41. 



The coefhcient of con-elation betw(>en mothers and daughters in winter egg 

 production was — 0.008±:0.048, in spring egg production +0.023iii0.050, total 

 egg production — 0.055 ±0.050 ; between the mother's individual performance and 

 her daughter's average performance in winter — 0.329±0.108, in spring +0.034± 

 0.121. The daughters show a greater variation than their mothers, but there 

 appears to be no appreciable correlation between daughter and mother in 

 respect to egg production ability. " The data so far obtained do not indicate 

 that egg-produciug ability is sensibly and directly inherited bet%veen mother and 

 daughter. There may be such an inheritance but further data are needed to 

 demonstrate it." 



Six hundred " unregistered pullets " which received precisely the same treat- 

 ment but whose mothers were birds ];>ying l)etween 150 and 200 eggs in their 

 pullet year were tested. The egg production of 350 of these is shown in the form 

 of frequency distributions. The means and constants of variation were deduced 

 and compared with the registered pullets. 



" The mean egg production of the ' registered ' pullets (daughters of ' 200-egg' 

 hens) is, with a single exception, smaller than the egg production of the ' uni-eg- 

 istered ' birds (not daughters of '200-egg' hens), regardless of the season of 

 the year or of the size of the pens in which the ' unregistered ' birds were kept. 

 The single exception to this rule is found in the comparison with reference to 

 spring production between the 'unregistered' birds kept in a flock of 10<J and 

 the ' registered ' birds. The ditference, however, in this case is small and only 

 arises because of the fact that the ' tmregistered ' birds in the 100-bird pen made 

 an exceptionally bad record during the spring months as compared with the 

 ether ''unregistered ' birds." The daughters of 200-egg hens do not conform so 

 closely to type as do tin* birds which are not daughters of 200-egg liens. 



The results of these investigations agree with those obtained by other workers 

 with different plants and animals and show that the chief, if not the entire, func- 



