THE EEL FAMILY. 451 



undergoes in its lifetime a migration from the sea to the fresh- 

 water lakes and rivers — eventually returning to the sea once 

 more to fulfil the law of reproduction, the conger, on the other 

 hand, never leaves the ocean and is essentially marine. The 

 former appears to require the sudden change to a marine 

 environment as a stimulus to the maturation of its reproductive 

 organs, whilst the latter having a permanent marine habitat, is 

 far more amenable to experimental research. It follows from 

 this that naturalists who have attempted to solve the eel- 

 problem have wisely led a flank attack upon its ally, the 

 conger, and with such success that every step gained in our 

 knowledge of the latter form appears to shed further light upon 

 the former. 



Several able observers, Hermes, Brock, Jacoby and others 

 have given detailed descriptions of the organs of generation of 

 the conger. Dr Otto Hermes in 1880 examined some congers 

 which had died in the Berlin Aquarium and made the discovery 

 of ripe spermatozoa in the milt (testes) of the male. This fact 

 at once had its effect upon • the ' eel question,' for, as already 

 stated, Dr Syrski had described organs in the male eel (which 

 have been known since as ' Syrski's organs'), which, he concluded 

 from their position and relationship, were the testes of this fish 

 (see Eel), and the organs which have a similar position in the 

 male conger being shown to be testes we have been enabled to 

 prove by deductive reasoning that Syrski's supposition was 

 correct. According to Hermes each testis is a thin elongated 

 organ suspended by a dorsal mesentery throughout the length 

 of the body-cavity. The organ is lobed — in his figure there are 

 five lobes on the right side and four on the left. From the base 

 of each testis leads a closed spermatic duct or vas deferens, and 

 the two join to open to the exterior behind the vent. This 

 male conger was 28 inches in length. The female organs need 

 not be here described in detail as they are closely similar to 

 those of the eel, and the similarity extends to the difference in 

 size between the sexes, the females being larger than the males. 

 The eggs are shed into the abdominal chamber and then 

 externally by the genital pore. 



The conger is enormously prolific, the number of eggs in 



29—2 



