REPORT OF COMMISSIONERS OF INLAND FISHERIES. 53 



nous that only by the closest attention can it be detected and then 

 chiefly because the eyes are prominent and of distinctive color. 

 Indeed, the first thought on seeing a school of leptocephalines may be 

 wonder that so many eyes are floating about. The diaphanous con- 

 dition is undoubtedly an efficient protection against many of the 

 dangers the larval eels encounter. Nevertheless it is only a partial 

 protection. The course of the young fishes riverward is beset with 

 danger, and this increases as the coast is approached. Fishes of the 

 high seas intercept many, still more become the food of the large 

 fishes of the banks of the coast, and of such is especially the cod. 

 That voracious fish rises to them and inflicts great slaughter." Dur- 

 ing the later stages the diaphanous character begins to be lost. 

 Gradually the pigment is developed, first on the end of the tail, later 

 in the neck, and lastly over the greater part of the dorsal and lateral 

 aspects. 



''The young eel or elvers that in spring commence their ascent of 

 the streams, which become their homes, must be the offspring of old 

 eels which left the streams not during the last autumn, but the one 

 preceding that; consequently, about a year and a half must intervene 

 between the time that a parent eel begins her procreative duties and 

 that when the offspring is ready to take up its life under similar con- 

 ditions. This is a history very different from any ordinary fish's, and 

 so far as known, unique outside of its genus." 



The rate of growth of the eel in fresh water has been investigated 

 by Gemzoe, by a study of the annual growth-rings on the scales. He 

 found that the young eel in Danish waters lives and grows for two 

 years after its arrival on the coast before the scales begin to develop. 

 At the end of that time it is about seven inches long. The scales, 

 according to his observations, grow only during the warm months 

 (June to September), so that each year they acquire a new growth- 

 ring. Consequently, the age of eels may be determined by count- 

 ing the number of growth-rings on the scales, and adding two years 

 for the time which the young eel spends in fresh water before the de- 

 velopment of its scales, and finally adding a year and a half for the 



