604 FRANK A. HAYS 
03 Cuart No XX 
Bi Grano Averase Measurement Curves oe 
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Saf) Au Service Groves 
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SSS ———— ee 
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4271p yl 
a “4 
1 ‘7 
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3.62 Gy 
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336 
te h 
3 ofS y 
jus ty 
27 
24 : 
AGE IN DAYS 
sa) 10; al See 3 50 ao 75 
charts where but a single litter makes up a graph a rather sudden 
break may sometimes be noted in the graph. This, in our 
opinion, is the result of error in measurement, and for this reason 
the graphs made up of several litters will be less influenced by 
minor errors and hence should be more representative of actual 
dimensions. 
In chart 22 are presented grand average graphs made up as 
the average of twenty-one Ist-service litters, fifteen 5th-service 
litters, eight 10th-service litters, and one 15th-service litter. 
Here the coincidence of the Ist-, 5th-, and 10th-service graphs 
is very striking. This fact bears out our previous conclusions 
from body weight studies that heavy sexual service of the male 
has no effect upon the growth of his offspring. Our evidence in 
studying the increase in the mean dimension does not show any 
effect on the progeny, from the heavy service of the male. The 
15th-service graph is made up of but one litter of two individuals 
sired by Male No. 1 and out of an average sized female. The 
fact that this litter is few in numbers and has as a sire the larg- 
est of the males will probably account for their larger mean 
dimension. 
