INTBKKAL CHAEAOTERISTICS OF THE SEXES. 641 



in the Eel, in its external form, as well as inner structure, so different from the ovary that it 

 could be considered as a partially developed or peculiarly shrunken ovary? According to all 

 researches which have up to this time been made there is the highest kind of probability that 

 this newly discovered structure is actually the long-sought male organ of generation. The inves- 

 tigator cannot, however, answer this question with complete certainty, since the thing which is 

 most necessary to the solution of this question, namely, the finding and the recognition of the 

 spermatozoa, has not yet been accomplished. 



In February, 1879, Professor Packard announced the discovery of spermatozoa in Eels from 

 Wood's Holl, Massachusetts, but soon after declared that this was a mistake, and that he had 

 been deceived by molecular movements among the yolk nuclei in the female organs. The discovery 

 of spermatozoa in the spermaries of the Conger Eel, recently announced by Dr. Hermes, of Berlin, 

 is, however, sufScient to demonstrate fully the correctness of Syrski's theory. The confirmation 

 in the case of the common Eel is solely a matter of time. 



Intbenal chabaotekistics of male and female Eels. — The differences between the 

 organs of sex in the Eel are well described by Benecke. The ovaries of the Eel are two yellowish 

 or reddish- white elongate organs as broad as one's finger, situated alongside of the backbone, 

 arranged in numerous transverse folds, extending through the entire length of the abdominal 

 cavity. They have no special opening to the outside of the body, and their contents must be 

 discharged into the abdominal cavity and must find exit through the very small opening situated 

 behind the anus. These two bodies, on account of their great size, are of course not easily over- 

 looked, but they contain such a great quantity of fatty cells and the eggs imbedded in them are so 

 small and delicate that one might easily believe, even after a superficial microscopic examination, 

 that the whole organ consists only of fat. While the eggs of other fishes measure from one to three 

 millimeters in diameter, and sometimes are much larger, still the eggs in the ovary of the Eel have, 

 on an average, a diameter of about one-tenth millimeter, and are so closely surrounded by fatty 

 ceUs with outlines much more strongly marked that it requires great skill to prepare a microscopic 

 slide in which they shall be as plainly visible as they are in the accompanying illustration, in 

 which they are magnified one hundred and fifty diameters. When a person has a microscope 

 which magnifies only one hundred diameters, it is best to put a portion of the ovary in water when 

 dissecting it, in order that the eggs may be easily found. It is much easier to find the eggs in 

 young Eels, seven or eight inches in length, than in adult fish, since in the former, although the 

 ovaries and the eggs are smaller, the fat cells have not made their appearance, and the eggs are, 

 therefore, plainly visible at the first glance through the microscope. The number of eggs is extra- 

 ordinarily large, amounting to many millions. The eggs of larger size which sometimes are found 

 in gTcat quantities in Eels that have been cut up, and have been considered to be eel eggs, have 

 always proved to be the eggs of other fish which they have swallowed, and in the course of cutting 

 them up have been found in the Eel's belly. 



The male Eels, which are found only in the sea and in the brackish water, are much smaller 



than the females, rarely exceeding fifteen or sixteen inches in length; in them, in the place of 



the ovaries in the female, are found spermaries, which differ in appearance in the manner shown 



in the illustration. These consist of two tubes which stretch the whole length of the body cavity, 



situated close to each other, and provided with numerous sacculations. Eipe spermatozoa are 



as rarely found in these organs as eggs ready to be laid have been found in the ovaries of the 



female. According to many accounts the male Eels, which later were found also by von Siebold 



in the Baltic Sea at Wis mar, differ from the females in the possession of a proportionally sharper 

 41 



