THE GERMAN CARP IN THE UNITED STATES. 561 
there. They worked continually up toward the chute, where the 
water poured in, heading for the most part in that direction, but 
turning and twisting slowly about. They became so numerous after 
a time that the upper ones seemed almost forced out of the 
water, and many were turned over on their sides at the surface. 
Figure 4, plate m1, shows a nearer view of the writhing mass of 
fish, all struggling to get nearer to the source of incoming water, 
though their movements appear rather slow and deliberate. Here it 
will be noticed that some of the fish are turned on their sides, and 
by the exposed backs it can be seen that they are nearly all headed 
in the same direction—to the right in the photograph. It was 
impossible to estimate the number of fish; there was no way of telling, 
in fact, whether they were mostly at the surface or whether they were 
as numerous deep into the water. I found, however, that at a distance 
of 20 to 30 feet away, where few backs were to be seen at the surface, 
an oar could not be put down into the water without hitting fish. 
Before long those nearest the chute began jumping out of water, some 
jumping to a height of nearly 2 feet into the air. Others made a 
jump and swam up the chute against the current as salmon leap a 
waterfall. Most were able to get up here but a short distance, while 
others worked up the whole length of the chute, some 6 or 8 feet, to 
the elevator itself. 
From the actions of the fish in the vicinity of the inflow it seems as 
though they must be reacting to the current. There is no direct evi- 
dence that the response is anywhere to the fresh water and not to the 
current, as it is evident that to any part of the pond where the fresh 
water comes so as to influence the fish there must necessarily be some 
current. The part that seems incredible is that it should so soon 
effect remote parts of the pond with sufficient strength to produce a 
positive rheotactic response on the part of the fish. It will be noted, 
furthermore, that if this is the correct explanation the response 
appears to be just the opposite of what has been given above for fish 
in the marshes when there is a change in the general water level of 
the river. There the fish ran with the current, spreading out over 
the feeding grounds; here they come against the current as far as they 
are able to come, and crowd about the inflow. What may determine 
the difference in the nature of the responses in the two cases I am 
unable to say. 
HIBERNATION. 
Most observers agree that during the cold months in the temperate 
regions carp seek the deeper holes in pond or lake, where they pass 
the season in a semitorpid condition. It is said that they assemble in 
circular groups with their heads together and pointed somewhat down- 
ward towards the mud. During this time they take no food, though 
they are said to decrease but little, if at all, in weight. I know of no 
F.C. 1904—36 
