173 - 



■ '.ring metamorphosis. 



III. Marrh— April 



Stage 5 

 (Average: 70*56 mm.) 



IV. June- 

 Stage 6 

 (Average : 65*70 mm.) 



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i'and HI, 



ca. 9 — I 



months; between III and IV, ca. ; 



mm. 



90 



88 

 86 

 84 

 82 

 80 

 78 

 76 



74 

 72 

 70 

 68 

 66 

 64 

 62 

 60 

 S8 

 56 

 S4 

 52 

 months. 



II shows the measurements of ca. looo 

 specimens of the 5th Stage (A and B), 

 taken on January 3rd igo6 in the Adour 

 river at Bayonne i'n France ^ 



III shows the measurements of the co- 

 lourless eel young (Stage 5 A and B) taken 

 in March and April 1905 in the North Sea 

 and Kattegat by A. C. Johansen and pub- 

 lished in his work (1. c, p. 6). 



IV gives the measurements of the pig- 

 mented young of eels in Stage 6 taken by 

 A. C. Johansen in fresh water in a stream 

 at Ribe in western Jutland in the middle of 

 June 1899 and published by him (I.e., p. 6). 



It appears from the table that almost 

 all the specimens in Stage 1 (I) are longer 

 than 70 mm. (i.e. are above the horizon- 

 tal line drawn and have an average length 

 of ca. 75 mm.). This is true also of the 

 specimens of Stage 5 from the month 

 of January (II). Here also almost all the 

 specimens are over 70 mm. (average ca. 

 73^2 mm.). We thus see that the reduction 

 in length during the 2nd, 3rd and 4th Stages 

 can only be quite inconsiderable as the 

 difference between the averages of the 1st 

 Stage (June) and 5th Stage (beginning of 

 January) is only a little over 1 72 mm. In spe- 

 cimens of Stages from March — April(III) 

 the one half approximately lies over 

 70 mm. the other half under (average 

 ca. 70V2 mm.), and finally we see that the great majority of Stage 6 from June (IV) 

 are under 70 mm. 



The average length has thus been reduced ca. 1 centimeter (from 

 ca. 75V4 to 653/4 mm.) during the whole metamorphosis from the 1st to the 

 6th Stage and almost 1 year has been occupied in the process. From June (1905) 

 to January (1906), i. e. from the 1st to the beginning of the 5th Stage the reduction in 



ciently proved in the present work; (i) that the different stages of development appear at definite j)eriods of 

 the year, as is described later (see Section 11, Chap. 5), 



I I have obtained these specimens through the Danish consul in Bayonne M. Charles Bailac, who sent 

 me some pounds of them. In Bayonne and other places in France there is a fishery for these eel young of the 

 5th Stage ("Pibale" or "Civelle"). The specimens were in formaline and were well preserved. 



