The Cyclostomes, or Lampreys 505 



the animals, even though they should regain their vitality. 

 A. Mueller, in 1865, showed that all the ova in the lamprey 

 were of the same size, and that after spawning no small re- 

 productive bodies remained to be developed later. This is 

 strong evidence of death after once spawning. 



"One author writes that an argument against the theory 

 of their dying after spawning can be found in the fact that so 

 few dead ones have been found by him. However, many can 

 be found dead if the investigator only knows how and where 

 to look for them. We should not anticipate finding them in 

 water that is shallow enough for the bottom to be plainly seen, 

 as there the current is strong enough to move them. It is 

 in the deep, quiet, pools where sediment is depositing that the 

 dead lampreys are dropped by the running water, and there 

 they sink into the soft ooze. 



"The absence of great numbers of dead lampreys from 

 visible portions of the stream cannot be regarded as important 

 evidence against the argument that they die soon after spawn- 

 ing once, as the bodies are very soon disintegrated in the water. 

 In the weir that we maintained in 1898, a number of old, worn- 

 out, and fungus-covered lampreys were caught drifting down- 

 stream; some were dead, some alive, and others dying and 

 already insensible, but none were seen going down that appeared 

 to be in condition to possibly regain their strength." 



Fig. 297a. Brook Lamprey, Lampetra Wilderi. (After Gage.) 



