EIGHTH LECTURE. 



THE BLIND-FISHES. 



CARL H. EIGENMANN. 



" An investigation into the history of degenerate forms often teaches us 

 more of the causes of change in organic nature than can be learned 

 by the study of the progressive ones." — Weismann. 



The Amblyopsidse are a small family of fishes of six or seven 

 species. Four or five of these live in the caves of the Missis- 

 sippi Valley. Amblyopsis is the largest of the species and has 

 the widest range, being found both north and south of the 

 Ohio River, and reaching a length of 135 mm. The structure 

 of these fishes will be dealt with in various journals. The 

 habits in general are given in the Popjilar Science MontJily for 

 1900. I shall consider here the reaction to light and the breed- 

 ing habits of Amblyopsis and the color of the Amblyopsidae. 



I. Reaction to LigJit. 



A long series of observations and experiments were made to 

 determine the reaction of Chologaster and Amblyopsis to white 

 and monochromatic light. Incidentally other characteristics 

 were brought out. The experiments need not be given in 

 detail here. 



Some previous experiments on blind or blinded vertebrates 

 may be recalled. Dubois ^ and Semper ^ record that Proteus, 

 the blind salamander of Europe, is sensitive to diffuse light. 

 Graber^ records that blinded salamanders prefer dark chambers 

 to light ones. Korange * notes that concentrated light deprived 



1 Compt. Rend., no, pp. 358-360. ^ ^^_ Akad. Wiss., 87, pp. 221. 



■^ Animal Life, p. 79. * Centralbl. of Phys., 6, pp. 3-6. 



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