THE EEL-F ARE 45 



they assume in miniature the semblance of their parents. 

 In the first period of change, the height of the body is reduced 

 so that a form of body results that is in the main eel-shaped. 

 Thus, out in the Atlantic, " glass-eels " or " transparent 

 elvers," are fashioned. " In contrast to the earlier flat 

 Leptocephalus stages these are now strong and swift as 

 arrows in their movements." During the second part of 

 the metamorphosis the length of the body is reduced, and 

 the elvers migrate, pressing in from the open sea to the 

 fresh water or the shallow coastal waters, where they can 

 complete their metamorphosis and begin again to feed and 

 grow. For the whole of the change is a fasting period, as 

 is so often the case in developmental transformations a 

 biological justification of asceticism. And it lasts about a 

 year ! 



The remarkable diminution in length, which occurs in 

 the metamorphosis from the Leptocephalus to the 

 " glass eel " stage, amounts to i centimetre, and careful 

 weighings of the two stages have shown that the meta- 

 morphosis involves an actual loss of substance, the dry- 

 weight of the " glass-eels " being only one-third of that 

 of the Leptocephali. That means, of course, that during the 

 fasting period of eight or nine months there is a literal con- 

 sumption of a considerable part of the material of the body. 



These results of the careful work of Dr. Schmid and 

 his colleagues can be readily enough summed up, but it 

 is of some importance to understand that the provisional 

 story of the life-cycle has been built up of numerous ob- 

 servations which were not very striking by themselves. 

 Thus we read that the captures in May were all Lepto- 

 cephali, while those in September were mostly in process 

 of metamorphosis ; that the later stages in September 

 were nearer shore than the earlier stages, which points 

 to shoreward migration during metamorphosis ; and so on. 



