480 ORREN LLOYD-JONES AND F. A. HAYS 
RATE OF MOTION 
Very few direct observations on the rate of motion of sperma- 
tozoa have been made. Bischoff (’42) reports that Henle ob- 
served mammalian sperm to move forward in a straight line at 
the rate of about 0.056 mm. per second. Lott (72) found that 
sperm taken from the epididymis of the dog move at the rate of 
0.06 mm. per second against a current under a glass slide. Our 
own work, as will be shown later, indicates a velocity for normal 
rabbit sperm of about 0.05 mm. per second. 
Many observations have been made, however, on the least time 
interval between the deposit of the semen and its arrival into the 
upper genital tract. Heape (05) finds that as a rule sperm of 
rabbit are to be found at the top of the uterus two hours after 
copulation and within the folds of the infundibulum two hours 
later. Coste (69, quoted by Hensen) states that in the rabbit, 
sperm are found at the ovaries two and three-quarter hours after 
copulation. The linear distance from cervix to fimbriae in the 
rabbit is about 280 mm. But if we wish to estimate the length 
of the path by which a sperm would cover this total distance by 
its own motile activity unaided by any other force, we should, 
on account of its devious lateral meanderings and the intricate 
folds of the surface over which it must travel, multiply the distance 
by at least 2. If we now allow three hours as the required 
time for this journey, the sperm would move at just about 0.05 
mm. per second. 
Data given by Payne (14) for the chicken show unusually 
quick action. He killed virgin pullets at varying intervals after 
breeding and reports finding sperm at the extreme upper end of 
the shell gland, a distance of about 650 mm. from cloaca, in one 
and one-half hours after breeding. Again, if we multiply this 
distance by 2 and if the sperm travel this distance unaided by | 
other forces, the rate would be 0.24 mm. per second. This is 
about four times as fast as any direct determinations which 
have been reported. Obviously, some other force, such as the 
aspirations of the os and peristalsis of the upper tract (Bischoff, 
42 Lott, ’72, Heape, ’98), is operating, and the interval elapsing 
