WHITE SUCKER 
153 
spermatozoa are motionless when removed by dissection from the body of the 
freshly killed fish and examined with the microscope, but the instant a drop of water 
is added they reveal an activity not exceeded in its rate and pandemic nature by the 
most active assemblage of protozoa or bacteria. One is reminded of chemical reac- 
tions in which every particle is thrown into violent motion. 
Spermatozoa from a male trapped on February 7 and measuring 8% inches 
in length showed the following periods of such activity in various media: Tap 
water, 40 seconds; water from a goldfish aquarium, 45 seconds; melted snow, 45 
seconds; human saliva, 5 seconds. The spermatozoa from a male that had been 
dead for one hour were nearly as active as this, though those from a fish four hours 
dead were inactive. In view of the excessive activity with which the male germ 
cells seek and fertilize the eggs during the minute or so of their swimming actions, 
it is possible to appreciate the advantage of both elements being discharged at the 
same time and over the same spot on the gravel. 
FERTILIZATION 
In nature this occurs during the moments following the discharge of eggs and 
sperm by the group of suckers engaged in the act of spawning. To obtain fertile 
eggs for study, a pair of ripe fish were taken from the traps on April 28 and removed 
to the Cornell University Fish-Cultural Experiment Station. Here the eggs and 
sperm were, by gentle pressure, expressed from the bodies of the live specimens into 
a small clean dish. The combined elements were stirred and allowed to stand for 
three minutes, after which water was added. Fertilization of well over 90 per cent 
of the eggs took place. That this occurred before the addition of the water, as is 
frequently assumed, can not be stated with certainty, as microscopic examination 
was not made until after the water was added. At that time the micropyle and 
implantation cone were clearly seen on several eggs. 
WATER HARDENING 
The egg when laid measures 2 millimeters in diameter. When water is added 
it begins to swell. The water enters through the shell or egg capsule, no doubt 
by way of the pores of the zona radiata, and lodges between the capsule and the egg. 
Within 30 minutes the eggs are quite turgid, have lost their partial adhesiveness, 
and may be handled without danger of causing injury. The capsule now stands 
one-half millimeter from the egg, giving a total diameter of 3 millimeters. The 
imbibed water probably functions to afford added protection from impact of sand, 
etc., prevent sudden changes of gases or liquids through the shell, and to permit 
movement of the embryo before hatching. 
CLEAVAGE 
A Meehan hatching jar was used with complete success. Such a jar provides a 
constant circulation of water from the lower end of an inserted glass tube upward 
through the eggs. The water used was from the creek, which is the source of supply 
for the station, so that conditions were as nearly natural as they could be made. 
A dozen eggs were taken daily, or often er at first, fixed in Gilson’s or Perenyi’s fluid, 
and preserved in 70 per cent alcohol. Examination was made of them in the alcohol 
