The Lake and Brook La?npreys of New York 441 



Nest Building and Spawning. — As spring approaches the 

 ovary in the mature lampreys increases greatly in size by the 

 addition of food yolk to the multitudinous ova. With the 

 male the actual increase in size of the spermary is not so 

 great, but the ripening sexual products act as a stimulus in 

 both sexes, urging them to complete the cycle of existence by 

 seeking again the clear brooks, far from the lakes, where they 

 themselves began an independent existence several years be- 

 fore. Apparently they start out independently from the vari- 

 ous parts of the lake, each one forsaking its prey, and swim- 

 ming vigorously or stealing a ride by attaching itself to the 

 bottom of some boat moving in the right direction. On they 

 go until the current of the inlet gives them the clue, and they 

 follow it. Frequently also ordinary fishes, bound on the 

 same errand, throng the streams, and then the lampreys, with 

 their inherent desire to be taken care of by the labor of others, 

 fasten to the larger fishes and are carried along up the stream. 

 It not infrequently occurs that from the natural inclination of 

 the stream or from some of man's obstructions, there are 

 rapids or dams to be surmounted. Nothing daunted the lam- 

 prey swims up just as far as possible by a tremenduous effort, 

 grasping a stone or other solid so that he should not be carried 

 down stream again, rests for a while and then by a powerful 

 bending and straightening of the serpentine body, a leap is 

 made in the right direction and what is gained is saved by 

 again fastening the mouth to a solid object. This goes on 

 until the obstacle is surmounted if it is not too great. Then 

 without waiting to think of the victory gained the lamprey 

 pushes on up the stream sometimes 8-10 kilometers until clear 

 water and numerous ripples are found. Just above some 

 ripple, the lamprey begins to make ready a secure place for 

 the beginning of a new generation. 



From the numerous observations on the brook lampreys it 

 appears that they are somewhat communistic or gregarious, 

 and join in considerable numbers, sometimes 8 to 10, to make 

 a common nest, but with the lake lamprey, while four or five 

 are sometimes in a large nest it more frequently happens that 

 but a single pair is present. If the situation is especially fav- 



