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Part III. — Thirteenth Annual Report 



Syrski noticed that a more advanced state of development of the egg was 

 found in those eels, in which the fissura recto-vesicalis and the genital 

 aperture were open, than in those eels in which they were closed. He 

 found ' that from the end of November till the beginning of March, in 

 ' many adult eels of 53 cm. and more, the ovaries were of the breadth of 

 ' 15-25 mm., and of a yellowish and sometimes reddish-white colour, pro- 

 1 duced by the development of adipose tissues and of blood vessels, and not 

 ' by the eggs filled with little globules of fat ; the genital aperture, and the 

 ' jissura redo-vesicalis were open. In other eels of a length of 60 cm. and 

 ' more, in which the genital aperture and fissura redo-vesicalis were closed, 

 1 the ovaries were less broad with but little fat, and of a mucous and almost 

 ' glassy appearance, so that the so-called vesicle [nucleus] and germinative 



* dots [nucleoli] were visible. The ovaries of young eels of the length of 



* about 50 cm. contained invariably but little fat, and the eggs were with- 

 ' out globules. The gradual growth and enlargement of the ovaries goes 

 1 on simultaneously with the opening of the genital orifice. According to 

 1 the quantity of fat contained in the ovaries, they have a mucous and 

 ' glassy, or more or less opaque or white appearance, or have small shining 

 1 dots.' From the end of March till October, he found in the majority of 

 eels which he examined, measuring from 60-70 cm. in length, that the 

 ovaries were scarcely white, and that the genital aperture was closed. 

 The larger eggs measured by him had a diameter of '2b-'2 mm. The 

 number of eggs contained in both developed ovaries reaches, according to 

 his calculation, five millions. Rubin found that the ovaries are full of 

 spherical ovules of a diameter of *l-'2 mm. during the whole year. ' It 

 would seem probable,' says Benecke,* 1 that the increase in the size of the 

 1 eggs in the wandering eels begins to be very rapid after August and Sep- 

 1 tember, while in the earlier months of the year, in all eels of moderate 

 4 size, the eggs were at the utmost 0'09 mm. in diameter. In September of 

 ' the same year it was found (on an average of numerous measurements) 

 ' that the eggs had a diameter of 0*10 mm., in October 0*16 mm., and in 

 1 November O^IS-O^ mm., while the eggs showed other characters con- 

 ' nected with approaching maturity, which earlier in the season are not to 

 ' be seen. All the eels which were captured later, in December and in 



* January, part of which came from rivers and harbours, part from the har- 

 ' bour of Putzig, had eggs measuring 0*09 mm., while very exceptionally 

 1 some of the eggs measured 0*16 mm., although among the fish examined 

 1 were some which measured 3 feet (about 91 cm.) in length.' The ovaries 

 of eighty specimens of the American eel (Anguilla bostoniensis), which 

 differs very slightly from Anguilla vulgaris, examined by Putnam,! were 

 in various stages of development. ' In two the ovaries were very small, 

 1 and the eggs in them exceedingly minute. From these the series showed 



* a gradual increase in the size of the ovaries and of their contained eggs to 



* the specimen exhibited, in which the eggs were still so small, as only to 



* be seen by a lens of considerable magnifying power, and not ready to be 

 ' excluded, though the ovaries themselves were large and full. The fact of 

 1 the great rarity of the eels with eggs, and the occurrence in these speci- 

 4 mens of ovaries in various stages of development, seem to show that in 



* contrast with the more usual slow development of the eggs in fishes 

 ' generally, the eels rapidly attain their seasonal development, the ovaries 



* immediately after the eggs are laid being reduced to a minute size.' 

 In an article on the 1 Breeding Habits of the Eel,' Packard J says, — ' As 

 1 far as we are aware, the eggs of the American eel were first discovered by 



* Brown Goode, ' Life History of Eel,' Bull. U. S. Fish. Comm., vol. i., 1881. 



t Proceedings Boston Society, xix., 1876-8. 



X Packard, ' Breeding Habits of the Eel,' American Naturalist, yo], xiii., 1879. 



