THE GYMNOTID EELS OF TROPICAL AMERICA. 191 
swim almost entirely with the long anal fin, the pectorals being used largely to 
guide the fish. All of this series were dead when visited the following morning. 
Series 4. Injury in Ventral Quarter. 
From the anal fin and anal muscles of ten specimens V-shaped pieces about 
20 mm. wide at the base were cut, so that the point of the ““V”’ pierced the body 
cavity for some five millimeters. These when dropped into the water made some 
rather feeble efforts to right themselves. 
Seven of them died during the two hours they were observed and the other 
three were found dead the next morning. 
Series 5. Surface Injury, Dorsal Quarter. 
Wedge-shaped pieces about 20 mm. long and 5 mm. deep were cut from the 
middle of the back in the region above the pectorals from five specimens. The 
tissue thus removed included only skin, scales and dorsal muscle. These injuries 
bled considerably more than those of Series 2, the entire surface of the wound being 
covered with blood shortly after the cut was made, and blood continued to ooze 
from the wounds for about five minutes after each fish was returned to the water. 
These injuries were apparently of little consequence to the fishes, for they swam 
about as actively and in the same fashion as their uninjured associates. On the 
following morning all were found alive and active. In each case the wound had 
begun to heal. 
Series 6. Deep Injury, Dorsal Quarter. 
From the same region as that operated upon in Series 5, wedge-shaped pieces 
about twenty millimeters long, and deep enough to remove a portion of the vertebral 
column, were cut from each of ten fishes. These injuries were such as to sever the 
vertebral column, the spinal cord and the dorsal blood vessel, the wound thus 
produced bleeding considerably. The injured fish when returned to the water 
made disconcerted efforts to swim but soon settled to the bottom. Here they 
maintained a half normal position or lay completely on one side. Blood continued 
to ooze from their wounds for about half an hour after the operation and when 
they were left at the end of an hour and a half most of them seemed almost dead. 
None of this series were alive next morning. 
In the above experiments the injuries which produced death during the first 
twenty-four hours after the operation were those inflicted in Series 3 (the removal 
of all of the body caudad of the viscera and air-bladder), Series 4 (the opening of 
the body cavity and air-bladder), and Series 6 (the severing of the dorsal artery, 
the spinal cord and the vertebral column in the suprapectoral region). Naturally, 
specimens regenerating such injuries were not found among the collections. 
The injuries of the other three series, Series 1 (loss of the entire caudal append- 
age), Series 2 (removal of the entire caudal appendage plus a small portion of 
