BULLETIN OF THE UNITED STATES FISH COMMISSION. 87 



elongate organs as broad as one's finger, situated alongside of the back- 

 bone, arranged in nunierons transverse folds, extending through the 

 entire length of the abdominal cavity. They liave 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 overlooked, 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 micro- 

 scopic examination, that the whole organ consists only of fat. AYhile 

 the eggs of other fishes measure from one to three millimeters in diam- 

 eter — and sometimes are much larger^still the eggs in the ovary of 

 the eel have, on an average, a diameter of about .1 millemeter, and are 

 so closely surrounded by fatty cells with outlines mu<;h more strongly 

 marked that it requires great skill to i)repare a microscopic slide in 

 which thej' shall be as plainly visible as they are in the accompanying 

 illustration, in which they are magnified 150 diameters. When a jierson 

 has a microscope which magnifies only 100 diameters, it is best to i)ut 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, 

 7 or 8 inches in length, than in the 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 great 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 15 or 16 

 inches in length; in them, in the place of the ovaries in the female, are 

 found sperraaries, 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. Eii)e si^ermatozoa 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 Yon Siebold in the Baltic Sea at Wismar, differ 

 from the females in the possession of a proportionally sharper snout, 

 less conspicuous dorsal fins, darker colonation of the back, a more 

 prominent and metallic luster upon the sides, the clean white coloration 

 of the belly, and the larger size of the eyes. I proiiose to reproduce 

 here the original descriptions and figures of Syrski, the discoverer of 

 the male eel. 



Having met, writes Syrslii, with many errors regarding the female 



