504 The Cyclostomes, or Lampreys 



they have to live in water without shade. Toward the end of 

 the spawning season, it is very common to see blind lampreys 

 clinging helplessly to any rocks on the bottom, quite unable 

 to again find spawning-beds. However, at such times they are 

 generally spent and merely awaiting the inevitable end. 



"As with the brook lamprey, the time of spawning and 

 duration of the nesting period depend upon the temperature 

 of the water, as does also the duration of the period of hatching 

 or development of the embryo. They first run up-stream when 

 the water reaches a temperature of 45 or 48 Fahr., and com- 

 mence spawning at about 50. A temperature of 60 finds the 

 spawning process in its height, and at 70 it is fairly completed. 

 It is thus that the rapidity with which the water becomes 

 heated generally determines the length of time the lampreys 

 remain in the stream. This may continue later in the season 

 for those that run later, but usually it is about a month or 

 six weeks from the time the first of this species is seen on a 

 spawning-nest until the last is gone. 



What becomes of Lampreys after Spawning? "There has been 

 much conjecture as to the final end of the lampreys, some writers 

 contending that they die after spawning, others that they return 

 to deep water and recuperate, and yet others compromise 

 these two widely divergent views by saying that some die and 

 others do not. The fact is that the spawning process completely 

 wears out the lampreys, and leaves them in a physical con- 

 dition from which they could never recover. They become 

 stone-blind; the alimentary canal suffers complete atrophy; 

 their flesh becomes very green from the katabolic products, 

 which find the natural outlet occluded; they lose their rich 

 yellow color and plump, symmetrical appearance; their skin 

 becomes torn, scratched, and worn off in many places, so that 

 they are covered with sores, and they become covered with a 

 parasitic or sarcophytic fungus, which forms a dense mat over 

 almost their entire bodies, and they are so completely debili- 

 tated and worn out that recovery is entirely out of the question. 

 What is more, the most careful microscopical examination of 

 ovaries and testes has failed to reveal any evidence of new 

 gonads or reproductive bodies. This is proof that reproduc- 

 tion could not again ensue without a practical rebuilding of 



