MIG RATING EELi^ 117 



SESSIONAL PAPER No. 38a 



Late in the evening when it begins to grow dark, they become very active, issuing 

 from their retreats, and heading up stream, one by one. 



All the eels were driven below the line of the lamps, and the latter lighted at 8.45. 



Experiment III. 



9.43. One ran past, but manifesting uneasiness returned to darkness a minute or two 

 later. I should have observed that the lights were only about 6 feet below the 

 upper screen, hence the intervening space was fairly well lighted up, but planks 

 across just below, made a marked line of division between the two. 



10.00 Another rvins past, but returns almost immediately. 



10.20. Another passes the light but goes back into the shadow at once. 



10.30. Another acts in a similar manner. 



11.10, One passes; three or four lying just below the line of light, but they soon 

 drew back. 



11.30. Another ran by. 



11.40. Another ran by. 



11.50. Another ran by. 



All of these soon returned to darkness. During the rest of the vigil an hour or 

 more, the fish as a whole lay in darkness, and, though restless and' active, avoided the 

 light. 



In a general way they repeated the movements of those observed in the trays — 

 approached the light cautiously, lay motionless for some time just below the lighted 

 line, then passed into and through the lighted area. It was not until the third night 

 that any rested more than a few minutes in the light. 



Though the fish were about the same size and could not be distinguished one 

 from another, the above record would seem to point to the majority or all of them 

 having passed the range of lamps during the night. They were fish fresh from the 

 sea, and their behaviour may be taken as representative of the species under similar 

 conditions, and hence had there been no screen above the lamps they would have all 

 passed and entered the lake. Still it must be noted that these fish had been impounded 

 eight or nine hours before the lamps were lighted, and their experience in the mean- 

 time, as well as the painful effects of changed osmotic pressure, may have, on the 

 first night at least, modified their otherwise natural actions. Still their movements 

 the next two nights were very similar; for a failure to secure fresh lots of fish, so 

 late in the summer, obliged the experimenter to use the same fish all the time. 



They always evinced a desire to run upstream at nightfall, but after eleven 

 o'clock very few attempted it, contenting themselves with remaining in the darkened 

 area, where they were often heard splashing and moving rapidly about, sometimes 

 trying to surmount the screen, at others twisting and turning violently in the middle 

 of the stream. With the exception of a few fry of the minnow, Coueslas plumbus 

 Ag., in the upper or lighted part of the inclosure, there was no food visible except a 

 few weeds here and there. 



Before closing the vigil one night, I looked over the lower part to see where the 

 fish were, when one was seen to scud away from the light of my lantern, which sug- 

 gested the trial of a moving light. Next night one was suspended over the middle- 

 of the stream, midway between the bullseyes and a little above, and kept swinging 

 crosswise the stream by means of a cord. For two or three hours none ventured to 

 pass, and hope ran high that the problem had been solved. They came up to the line 

 of light beforementioned, and pushing the head just beyond, lay motionless for a 

 half hour or so, as if watching the moving object, then they lyithdrew, only to repeat 

 the action some minutes later. About midnight, however, one after another gradually 

 drew into the lighted area, until all I had impounded were lying side by side, only a 

 few inches apart. One after the other, curving the anterior half of the body upwards 



