178 Conservation Department 



The transformation begins in the summer. Some have been 

 found commencing as early as the middle of July. From this time 

 all along through August, and sometimes the first signs begin early 

 in September. The transforming lampreys remain in the mud and 

 sand the same as larvae, but they are more often found in deeper 

 water. The time required for the transformation is more easily 

 determined than for either the larval or the adult life. This is 

 because it is shorter, and during the transformation time, no food 

 is taken by the lamprey. 



In 1897 and 1898 especially, but repeated occasionally for the 

 next fifteen years, large larvae and those showing the beginnings 

 of transformation have been kept in an aquarium with sand and 

 gravel and stones on the bottom to simulate the natural stream. 

 As stated above, these transforming animals remain under the 

 sand and gravel like larvae until they are ready to commence their 

 predatory life. They do not all begin their transformation at the 

 same time, and naturally do not all finish on the same date. When 

 they are ready for their free life in the water they leave the cov- 

 ering of sand and appear above it in the water. Some come out 

 during the last of January, and others during February, and some 

 as late as March. 



Fish of different kinds, bullheads and carp, have been put into 

 the aquarium to serve as food for the young lampreys if on emerg- 

 ing they were ready for it. They certainly were ready and pounced 

 upon the poor fish like a pack of wolves (Fig. 1, No. 4). 



The aquarium experiments have been confirmed by the actual 

 happenings in nature, for the fishermen have brought to the 

 laboratory young lampreys caught on fish in January, February, 

 March and the later months. It can be affirmed then with confi- 

 dence that in nature it takes the transforming young lampreys be- 

 tween six and seven months, that is from the middle of July to the 

 middle of January, or for those commencing in August, until Feb- 

 ruary and the beginning of March, to complete the profound modi- 

 fications in structure to render them adapted to their free-swim- 

 ming, predatory life. These experiments were made with lake 

 lampreys, and from the stages of growth found with the large sea 

 lamprey larvae and transforming young, it seems highly probable 

 that they are an equal time in changing from the larval to the 

 adult stage. Indeed the more one studies the marvelous changes 

 that occur, the less one wonders that it requires six months or more 

 to complete them. 



Brook Lamprey Not Parasitic. — The changes undergone in 

 the transformation of the brook lamprey are almost precisely like 

 those in the sea and the lake lamprey. The time they remain cov- 

 ered in the sand and gravel of the stream is considerably longer, 

 and the subsequent life is markedly different. This was shown in 

 1897-1898, and has been repeatedly confirmed many times since 

 that original experiment. 



