Biological Survey — Oswego Watershed 179 



The very large larvae and those showing signs of change were 

 kept in an aquarium with sand and gravel and with running water 

 flowing over them as in the natural stream. Small bullheads were 

 put in the aquarium for them to feed on if they wished when they 

 emerged. But they paid no attention to the fish. Their sucking 

 mouth, piston-like, rasping tongue and the horny teeth on the oral 

 disc seemed to fit them for parasitism, but they never molested the 

 fish. It was noticed, however, that when they attached to the sides 

 of the glass walled aquarium that they looked very much as do the 

 ones that are on their way to the spawning ground. That is, one 

 could see the eggs through the thin wall of the body ; and later 

 after they were shed into the abdomen they looked like little pills 

 in a homeopathic vial (Figs. 1, No. 5; 2, No. 1). 



To make sure that such apparently, premature ripening of the 

 eggs also occurred in nature, my trained lamprey digger and 

 catcher was commissioned to get specimens from the Cayuga lake 

 inlet. In these the eggs and milt were well advanced toward 

 maturity, but not quite so far as with those in the laboratory 

 aquarium with the warmer water. 1 



This experiment and its subsequent verification proved conclu- 

 sively that the brook lamprey is not parasitic, but like many 

 insects lives its growing life in the larval state, and during its 

 adult life does nothing but look out for the next generation and 

 then die. In 1897-1898, it was almost or quite universally believed 

 that the brook lamprey with its apparently complete armature for 

 parasitism, was really parasitic (Fig. 1, No. 2). The experiments 

 at That time, were the first, so far as I know, to really set the 

 matter at rest. And now it is universally understood that the 

 brook lamphrey in all regions is non-parasitic, and that its free life 

 in the water is only a few weeks in length, only long enough for it 

 to reach the spawning grounds , build its nest, lay its eggs and 

 care for the nest a few days. Its life work is then finished. 



A very interesting anatomical fact was recently brought out by 

 Keibel, 2 viz., that in the German brook lamprey, while it under- 

 goes apparently all the transformation changes, the oesophagus 

 does not become hollow all the way from the throat to the 

 intestine, but for a short distance near its cephalic end contains a 

 solid plug of epithelium. This is true of a goodly proportion of 

 the American brook lampreys, but by no means of all. Many of 

 them have the oesophagus open the entire distance as with the sea 

 and the lake lamprey. Of course those with a solid oesophagus 

 could not swallow the blood if they were to suck some from a fish, 

 but the American ones with open oesophagus could do so. But 

 none of them ever attack a fish. 



No doubt the brook lamprey was at one time parasitic the same 

 as the lake and the sea lamprey. Even now its first cousins 



1 Gage, S. H. Transformation of the brook lamprey (non-parasitism). 

 Proc. Amer. Assoc, Adv. Sc. Vol. 47, 1808. Science, 1898, p, 401. 



2 Keibel, Franz. Eroetfmingsansprache der anatomischen Gesellscliaf t, Wien. 

 Anat. Anz. Bd. GO, p. 3, 1925. 



