126 Fortieth Annual Meeting 



jected to this cold water only a short time ; yet nearly all 

 of them had been attacked by a small flagellate parasite, one 

 that is especialy hurtful and causes more gill inflammation 

 in young trout and other young fish than any other para- 

 site known. Nearly all of the bass had this parasite. Many 

 individuals had under the skin the larvae of a flatworm, 

 which, as you know, does not do great harm because the 

 fish is not the final host of the worm. A few bass had in 

 the eyes what the Germans call Saugzviirmern, nematode 

 larvae, to the number of perhaps 200 or more, causing 

 blindness. 



This condition was observed some years ago at the 

 Oneida Station in the trout perch and other fish. The trout 

 perch is one of the most valuable natural foods of the pike 

 perch. A number of young bass had these nematode larvse 

 in the eye, flagellates in the gills, and also distomes making 

 little black specks under the skin. At the Oneida Station 

 young black bass, yellow perch and a half dozen other 

 species which run up the creeks from Oneida Lake in the 

 spring are frequently attacked by this larval worm which 

 invades the eye. Hofer describes a species which produces 

 the same effect in Germany. This condition was not 

 observed in Scriba and Frederick Creeks, at Constantia, 

 until 1902, although it existed earlier. It lasts until freezing 

 weather sets in and affects all kinds of small fish, but is 

 not seen in large fish. The disease begins suddenly and 

 destroys the eye in three or four days. It has never been 

 observed in the creeks mentioned above the dam. 



No study of this disease has yet been made from suitable 

 material, Mr. Marsh saw some examples from Constantia 

 in 1906, but was unable to decide whether the disease was 

 of bacterial origin or not. The condition may have arisen 

 subsequent to the original attack of the parasite. The 

 disease has not been studied since 1906, but I think there 

 is now no doubt now that the larvae of one of the nema- 

 todes cause the blindness. 



In June, 1905, a bass caught in Culver Lake, New Jersey, 



'*» J 



