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Show 1901.] FROM BRITISH EAST AFRICA. 347 The case is, I believe, different with the spermatophores of an earthworm which it is the object of the present paper to describe. Ihe species upon which m y observations were made is of the genus Stuhlmannia, an East-African Eudrilid whose general anatomy was detailed some years since by Michaelsen. I am in possession of a quantity of examples of that worm which are in an excellent state of preservation for microscopical work. This Annelid, like other Eudrilida?, has no true spermatheca? like those of the majority of earthworms, unless, indeed, the actual external orifice of the pouches and the epithelium which passes from the epidermis of the body-wall for a short way into the interior be regarded as the equivalent of the spermatheca?; it has capacious sacs which are probably (in other forms of Eudrilida? certainly) formed by the peritoneal epithelium, and whose cavities therefore are ccelomic. They are lined throughout by an epithelium of tall columnar cells, whose characters I shall atteud to in detail immediately. In the spermatheca? are frequently to be found masses of spermatozoa which are not compacted together by any cementing material apparent on staining, but which seem to be perfectly free and floating spermatozoa. This was the case with some examples which 1 studied. In two or three were these masses of spermatozoa compacted into spermatophores, which are always contained in the median sac1. The spermatophores of Stuhlmannia differ from those of any other 01igocha?ta whose spermatophores are known. Their characters are somewhat intermediate between the two types which these organs present in the Order. It will be recollected that in the Lumbricidae, in Criodrilus, and in Alma the spermatophores are chitinous cases open at one end, but quite impervious elsewhere, of not very elongated form, which are found attached to the body-wall of individuals belonging to these genera in the vicinity of the generative pores. To this type belong also the spermatophores of one genus of Tubificiche, Bothrioneuron, which has essentially similar spermatophores, and which, in accordance with their structural resemblance to those of theLumbricida> and the other genera mentioned, are attached to the body superficially. On the other hand, in the Tubificida? (Tubifex, Limnodrilus, Psammoryctes, Clitellio), and in the genus Polytoreutus among the Eudrilida?, the spermatophores are elongated structures, with often an aperture at one end, and always with the ends of the spermatozoa projecting through their chitinous (?) walls. These spermatozoa are capable of individual movement, which results in a movement as a whole of the spermatophore. They are invariably found in the spermatheca?. Of the first kind of spermatophores, it is certain now that they are formed by the epithelium surrounding the terminal male efferent apparatus. The second kind of spermatophores seem to be, in the case of the Tubificida? at least, moulded in the spermatheca1, though the precise nature of their origin is 1 See below (jp. 351) for a description and figures of these sacs. |