SEXUAL ACTIVITY OF MALE RABBITS 591 
TABLE 1 
Average birth weight of litters sired by the three different males used, by service 
groups 
Ist 5TH 10TH 15TH 207TH 
MALE 
se a ues Weight Bs Weight oe Weight Blame Weight Sony Weight 
1 6 46.7 6 45.2 7 45.2 7 ono) 1 59.7 
3 12 50.9 8 45.0 2 45.0 2, 42.7| 00 00 
4 8 42.4 6 58.8 4 58.8 4 49.6 6 DOeO 
Weight at ninety days 
1 5 {1209.5 3 /1236.6 @ 123821 7 {1262.0 6 |1299.3 
3 11 /1170.0 6 127.8 7 (1095.3 2 {1270.7} 00 
4 7 {1054.9} 6 |1096.1 5 (1424.3 2 {1199.7 3 {1009.0 
could be expected to keep ahead of the other classes of offspring 
at least for ninety days. This way of explaining the position 
of the 20th-service graph above the others is called in questions 
by chart 3 and also by table 1. The graph of the 20th-service 
litter lies below the others. This graph represents the growth 
of a smgle 20th-service litter (after the first weight) also by 
Male No. 1 and out of the heaviest female in the breeding stock 
(No. 15). Therefore, the fact that this litter lies below 5th- 
and 10th-service litters on this chart cannot be explained as the 
result of small ancestry. 
Table 1 shows that the size of the male ancestor is not a 
very important factor in relation to the size of the young at birth. 
At the age of ninety days, however, the effect of the heavier sire 
becomes more important, but nevertheless is probably not as 
important as some other factors concerned as will be pointed 
out later. 
When we consider the 15th-service group, we find that seven 
litters were sired by Male No. 1, two by No. 3, and four by 
No. 4. Again we should expect a more uniformly heavy progeny 
than if all males had contributed an equal number of litters to 
the data. Chart 8 shows the superiority of the 10th-service 
group over the 15th-service group up to the fifty-fifth day, 
after which time the graph rises above all others. 
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