468 ORREN LLOYD-JONES AND F. A. ‘HAYS 
BEHAVIOR OF MALES 
The act of coition is of very short duration in the rabbit—one 
or two seconds suffices. The male generally mounts the female 
at once; when she is in heat she will raise her hinder parts and 
elevate the vulva. By a single thrust of the male the act is 
completed, and the force of the thrust varies with different 
males. . 
The time interval between services is influenced by many fac- 
tors; the following circumstances tend to prolong the service 
interval; a high temperature in the laboratory; indifference of 
the female; heavy service by the same male a few days pre- 
viously; a large number of copulations on the given day; allow- 
ing the female and male to remain together in the same cage 
after coition; failure to furnish ‘fresh’ females after the male has 
served the same operated animal several times; failure on the 
part of the experimenter to crowd the male to his maximum. 
The time interval between services ranged from five minutes in 
the early part of a given series to as much as twenty minutes 
in the latter part of the series. The great majority of services 
were made at intervals of ten minutes. 
Twenty services in the space of about three hours is not the 
utmost that a rabbit can do; in our own work they have occa- 
sionally made several more. However, this was chosen as a 
safe upper limit, for on many more occasions we have been 
unable to induce the male to perform as many as twenty services 
in an afternoon, there being in these cases a complete tempo- 
rary loss of desire. Several days were required for males to 
fully recuperate from a long series of services. It was the aim 
to allow at least seven days’ rest between heavy-service days. 
When such series of matings follow each other too closely the 
males were unable to copulate even though they made pro- 
nounced efforts. 
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VOLUME OF SEMEN RECOVERED 
The greater mass of the seminal fluid is made up by secretions 
from the accessory glands. These are true secretory glands, 
and if their behavior is analogous to other glands of this class, 
