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XIY. On the Dioecious Character of the Botifera. By Philip Henry Gosse. 
Communicated by Thomas Bell, F.B.S., P.L.S., F.G.S., 
Professor of Zoology in King's College. 
Eeceired February 19, — Eead March 13 and April 3, 1856. 
1. When Dr. Ehrenberg, in 1838, published his ‘ Infusionsthierchen,’ containing his 
matui’ed conclusions respecting the Botifera, he defined the Class as consisting of 
animals all the individuals of which are hermaphrodite, oviparous, and ovipositing. The 
hermaphroditism, or “ dualism of the sexual system,” he described as consisting of “ an 
ovary, simultaneously developing a few great eggs ; two thread-like male sexual glands, 
thicker and club-shaped m front, and a contractile bladder, placed near the cloacal ori- 
fice, uniting the hermaphrodite organs for self-impregnation.” 
2. These conclusions remained unchallenged till 1848, when Mr. Brightwell 
announced his important discovery of separate sexes in a Botiferous animal, since named 
Asplanchna. The presence of the tortuous threads in both sexes, and of the contractile 
bladder in the female, at once negatived the conclusions of Ehrenberg, that these were 
male impregnating organs, though their functions were still undetermined. 
3. This single example, however, was by no means sufficient to overthrow the presumed 
hermaphroditism of the Class as a whole ; though it naturally threw doubt on statements 
as yet unhesitatingly received. The case might have been one of those solitary excep- 
tions, which occasionally mock oui’ generahzations ; like the exception to the law of 
metamorphosis in Gecarcinus and Astacus ; or to that of immediate relation of impreg- 
nation to birth, in Aphis and Daphnia. 
4. In the “Annals and Magazine of Natural History” for July 1850, I published 
some observations on a second species of Asplanchna [A. priodonta), in which I described 
and figured the male. Soon afterwards I had the pleasure of repeating and verifying 
those of Mr. Brightwell and Mr. Dalrtmple on A. Brightwellii. 
5. The dioecious character was thus extended from a species to a genus. Since then, 
I believe, no advance has been made in our knowledge of the sexual relations of the 
Botifera, from actual observation, save the discovery of a third species of the same 
genus. Dr. Franz Leydig, in a recent able memoir * on this Class of animals, announces 
that Notommata Sieholdii has distinct sexes ; and that the male, while exhibiting some 
curious peculiarities of external form, agrees with that figured by Mr. Dalrymple, in all 
essential points. He appears not to have been aware of my observations on A. priodonta. 
* “TJeber den Ban, und die systematisclie Stellung, der Baderthiere'' (Siebold and Kollikee’s Zeit- 
schrift, July 1854). 
MDCCCLVII. 2 T 
