SEXUAL ACTIVITY OF MALE RABBITS 593 
TABLE 2 
Number of litters included in graphs of charts 1 to 12, inclusive, and the male 
, ancestry 
SERVICE GROUP 
MALE 
MEMBER : 
Ist 5th 10th 15th 20th 
1 6 6 7 7 11 
3 12 8 7 2 
4 8 6 6 4 6 
Concerning the graphs for the 10th-, 5th-, and 1st-service 
litters, we note that as a rule the Ist-service litters are inferior 
in weight to either the 5th- or 10th-service litters and that the 
10th-service litters are for the most part superior to the 5th- 
service litters. As previously noted, less favorable environment 
and greater immaturity of some of the female animals are thought 
to be the chief factors entering here. The male ancestry is 
almost uniformly distributed among the three males. Below 
we note from the table just how the ancestry is distributed. 
Table 2 shows us that the three males are about equally dis- 
tributed in the progeny groups from the 5th and 10th services. 
In the Ist-service group, however, No. 3 has sired twice as many 
litters as No. 1 and 50 per cent more than No. 4. Since Male 
No. 3 is a smaller animal than No. 1, we have here a partial 
explanation for the apparent inferiority of the 1st-service litters 
over all others. In the 15th- and 20th-service groups the prog- 
eny of Male No. 1 predominate, and Male No. 3 sired no litters 
in the 20th-service group. 
A word of explanation in regard to a few remarkable features 
of some of the charts may be of value at this point. On chart 3 
the depression in the 5th-service graph at sixty days is due to a 
failure to obtain data on.the heavier of the two litters making 
this graph. This particular litter was unintentionally over- 
looked for four weighings. On chart 5, the drop in the 10th- 
service graph at sixty-five days is due to the incomplete record on 
one litter at the time the graphs were constructed and this litter 
was made up of very heavy individuals. 
