IK) Thirl ii-scvcnth AintudI Mcetlnij 



breed in fresh water, or anywhere near fresh water. It is liard 

 to pursiuule some men that sneh is the ease, but nevertheless it 

 is a fact. 



Now the eels not only do not l)ree(l in fresh water, bat they 

 go a long distance out to sea before they are able to breed. Up 

 to the time that they are foimd in the estuaries and the fresh 

 water of rivers, they still are destitute of developed ovaries and 

 spermaries, unless examined with a microscope when these or- 

 gans may l)e seen in a rudimentary condition. 



The eels then go out to sea, so far as regards tlie northern 

 European species, going out into the Atlantic Ocean, into water 

 of the depth of at least a thousand meters: tliat is. over 500 

 fathoms to put it in round numbers, and it is only under such 

 conditions that they can breed. Meanwhile as they are ad- 

 vancing into tliese deptlis doubtless the ovaries and spermaries 

 l)econie develo])ed, and the eggs must be deposited in the de])ths. 

 But they are floating eggs, having oil globules they ascend to- 

 wards the surface. They are at last hatched and in the later 

 months of summer or fall, young eels are found perhaps hun- 

 dreds of miles from the coast on the high seas as leptocephali. 

 Now it must take some months to ])ass through the condition 

 from the time that the mother eel leaves the estuaries until the 

 time when those eggs are develo])ed and the young leptocejthali 

 ai)])ear at the surface or near the surface. 



These young then come out in the form of leptocephali. en- 

 tirelv unlike the mother eel, being very transparent, ribo]i like, 

 very high and very much compressed, so unlike the mother I'el 

 that some ichthyologists long considered the leptocephali, which 

 are merely the young of the various eels, as being a distinct 

 order of fishes. For many years one species from northern Eu- 

 rope was known as the leptocephalus morrisi. That form was 

 long the only one known, and that is nothing l)ut the young of 

 tile conger. It is only within a few years tliat two eminent 

 Italian naturalists discovered the true nature of the leptocephal- 

 us form of eel and connected by graduation this leptocephalus 

 form with the eel. It was a species that had been only known 

 before as found in the Mediterranean. Now it was believed, 

 by some at least, that the common eel was generated in the same 

 way as the conger, that is, by means of a leptocephalus: but this 



