G56 NATURAL HISTOEY OF AQUATIC ANIMALS. 



Question 1. How can the fact be accounted for that no one has ever found mature females and 

 males, spawners and milters, among the Eels? 



Answer. The Eels require the influence of sea-water for the development of their reproductive 

 organs. As is now definitely understood, they leave the rivers and the brackish lakes on account 

 of the undeveloped condition of their reproductive organs, for the purpose of becoming sexually 

 mature at sea. That these migrations to the sea take place for the purpose of reproduction appears 

 to be certainly proved by the fact that the young Eels leave the sea in the sprihg, and that the 

 migrating Eels, like other fishes at the spawning season, abstain from eating. 



Q. 2. When and where occurs the necessary development of the reproductive organs of the 

 Eel to a condition in which they are capable of fertilization ? 



A. Development of the reproductive organs takes place iii the sea, not close to the shore, 

 but at a distance and in deep waters. This development is extraordinarily rapid, when the 

 immature state in which the migrating Eels are found is taken into consideration; they must 

 become sexually mature within a few, probably five or six, weeks of the time that they enter the 

 sea. At Comacchio the emigration takes place between the beginning of October and the end of 

 December. 



Q. 3. Where does the act of spawning take place, the fertilization, and the deposition of 

 the eggs ? 



A. There are probably certain definite spawning places in the sea, off the mouths of the 

 rivers. These are the mud-banks to which the Eels go, for the purpose of spawning, in great 

 numbers. The young fish are developed upon these mud- banks, and from eight to ten weeks 

 after their birth, at the beginning of spring, find their way to the mouths of rivers, which they 

 ascend. 



Q. 4. What becomes of the grown-up Eels after spawning time, and why do they remain 

 lost to sight and never again come back into the rivers ? 



A. The old Eels, male and female, without doubt, die soon after the spawning season. 

 The very unusual rapid development of their reproductive organs has such an effect upon the 

 systems of the adult Eels that they die soon after the act of reproduction. That is the reason 

 why they are never seen to wander back again. 1 



An intelligent Chioggian, the owner of a fishing vessel, in answer to my question as to where 

 the old Eels staid, answered, " They die on the mud-banks after they have propagated their 

 young." 



This hypothesis may be confirmed in a scientific manner by the analogous circumstances in 

 the history of the Lamprey. Panizza, in his description of the sea Lamprey, Petromyzon marina, 

 remarks that both the males and females of this species after the spawning period are brought 

 up dead. Concerning the river Lamprey, P. fluviatilis, Statins Miiller remarks that when they 

 spawn they slowly fall away and die. Concerning the little Lamprey, P. planeri, August Miiller, 

 the discoverer of its larval form, has recorded the same opinion. 2 



192. THE CONGER EEL CONGER, OR LEPTOCEPHALUS CONGER. 



The Conger Eel is occasionally seen in the summer on the coast of the New England and 

 middle States, and is known to our fishermen as the "Sea Eel." No observations have been 

 made of its habits by American zoologists. 



'As a confirmation of this view, von SieboM was the first to make this hypothesis. 

 "Op. cit., pp. 53-56. 



