164 MEMOIRS OF THE CARNEGIE MUSEUM. 



on this side that each unit receives its nerve-fibers. It is not, however, intended 

 here to discuss the microscopic structure. 



Aside from the electric organs the anatomy of the electric eel is very similar 

 to that of the other Gymnotids. 



2. Nature and Strength of Electric Shock. 

 Sachs states that the electric shock may be received in four ways. 



1. By completing an electric arc. 



2. By conduction. 



3. Direct contact. 



4. From the water in which the eel is discharging shocks. 



1. Sachs considers an arc to be completed if the electric eel is touched at two 

 points. He found the maximum shock was received when the connections were 

 made just behind the head and at the end of the tail. This of course included 

 the entire mass of electric tissue. Sachs accidentally made such an arc with an 

 eel three and one-half feet long. Its head fell on one foot and its tail on his other 

 leg. The contact lasted for about thirty seconds, during which time Sachs was 

 unable to move. He experienced great pain the rest of the day and soreness of the 

 limbs for some time afterward. Humboldt tells of stepping on a four foot eel in 

 such a way as to make a head and tail connection and being instantly knocked 

 down by the shock received. Dr. Eigenmann relates that all of the fishes taken in 

 a haul of a large seine were killed by an electric eel, which was among the catch, 

 while the seine was being pulled in. The experiments of Sachs showed that the 

 strength of the shock varied directly with the amount of the electric tissue included 

 in the arc. 



2. and 3. Direct contact in but a single place on the fish is also capable of 

 transmitting a shock, if the ground completes the circuit. A severe shock can 

 be received if the eel is only touched by a finger. In the same way the shock can be 

 inflicted through wet wood, cordage, metal, or any other conductor. Glass and 

 rubber are insulators against it. 



4. The hmit of the effectiveness of the shock in water has never been deter- 

 mined. Sachs gives several cases of the transmission of the shock in this way. 

 Mules are often knocked from their feet while fording small streams frequented 

 by the eels, without actually being struck by them. Natives attempting to get 

 out of a boat into the water are frequently unable to get either in or out after 

 touching the water if an eel is near by, until the shock ceases. On account of such 

 occurrences the natives regard these eels with great fear and hatred, killing them 

 when opportunity offers. While experimenting with eels in wooden troughs, 

 Sachs found they were able to kill frogs, fishes, and freshwater shrimps (contrary 

 to the idea that the last mentioned form is immune) at a distance of several feet. 



A careful count of the number of shocks given by a single eel was made by 



