186 Conservation Department 



isfactory case a lamprey attached itself to a bullhead (Ameiurus) 

 at 8.30 a. m. January 14, 1914. At 9 p. m. January 19 the lam- 

 prey was still attached, and the bullhead seemed greatly dejected. 

 At 5 a. m., January 20, the lamprey had released the bullhead. 

 It showed a savage hole in its side where the lamprey had been 

 attached. In this case the lamprey had been with the fish for 

 about five days. From this experiment, then, it would appear 

 that a lamprey remains only a few days attached to a single fish, 

 and when its hunger is completely satisfied it lets go of the fish 

 and swims freely in the water. This conclusion is supported by 

 the observations of fishermen that lampreys often attach them- 

 selves to their boats and sometimes to the oars. 



The confirmation is emphatic in the lamprey given me by Pro- 

 fessor Smallwood. This was found clinging to the rudder of 

 their boat when they returned from a cruise in Oneida lake. On 

 opening the lamprey it was found with the entire intestine filled 

 with blood. Further confirmation is given by fishermen who some- 

 times find on a single large fish several lamprey marks, some fresh 

 and some partly healed. 



Taking all the evidence of personal observation, the attach- 

 ment of lampreys to boats and partly healed lamprey scars on 

 fish, it seems certain that, as with the laboratory experiment, a 

 lamprey remains with one fish only a limited time, when both go 

 free. When again hungry the lamprey hunts up a new victim. 



(c) With reference to the frequency of their meals: Naturally 

 their meal time must be rather irregular, but judging from the 

 observations made in the bathtub experiments it seems to be once 

 in about three weeks. This conclusion is reached because the 

 lampreys brought fresh from the lake in December and January 

 always had the intestine full of blood. These were kept in the 

 bathtub with fish. The one described above in (b) came December 

 9, and remained in the tub with the fish until January 14 before 

 attacking the bullhead for a new food supply. In this case the 

 lamprey went 36 days without seeking food, when plenty of it 

 was in sight all the time. It then took about five days to get a 

 new supply from the bullhead. This experiment shows then that 

 the lampreys need a full meal about once a month. 



(d) For determining the nature of the food of the lamprey 

 many have been killed immediately upon their receipt from the 

 lake, and the intestinal contents examined both with the naked 

 eye and with the microscope. The one described in (b) above 

 was studied with especial care for it could be investigated within 

 a very short time after it had liberated the fish. There was found 

 first of all blood. The color alone might have been sufficient, but 

 it was put under the microscope and the blood corpuscles, and 

 blood crystals demonstrated. Then it was subjected to the spec- 

 troscope and the characteristic absorption spectra found. 



In the second place there was a small amount of minced 

 striated muscle, and some connective tissue with fat and pigment 

 cells. The presence of the muscle, the connective tissue and the 



