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Show 1887.] ANATOMY OF EARTHWORMS. 379 brought about. The adult structure of the supposed ovary of segment 14 might otherwise be regarded as an exaggeration of the partial continuity of the receptaculum ovorum and the oviduct which exists in Lumbricus he.1 The continuity between the oviduct and the ovary is a fact of some little importance in the comparative morphology of Annelids. In no other form that I am aware of is there a similar connection between the gland and its duct, the two being invariably separate. There is therefore a difference between Eudrilus and other Lumbri-cida_>, like that which exists between Lepidosleus and many Tele-osteans on the one hand, and Osmerus and Amia on the other2. It may also be remarked that, at any rate in this particular, it is impossible to draw a hard-and-fast line between tbe Hirudinea and Annelida ; hitherto the Hirudinea have been regarded as differing from Annelids in the possession of what have been termed "tubular ovaries," where the duct was supposed to be an outgrowth or continuation of the gland itself. Recently Ntissbaum3 has stated that the reproductive organs in certain Hirudinea are developed independently of their ducts, which have a resemblance to nephridia. It is plain therefore that in this case, at any rate, the distinction between tubular and other ovaries falls to the ground. It is interesting to note that the condition which is characteristic of the Leech may also occur in a Chaetopod. Male Generative Apparatus.-In spite of the fact that Hering 4 clearly demonstrated the true testes of Lumbricus, and distinguished them from the vesiculae seminales, the latter structures have until very lately been called " testes." The rediscovery by Prof. Bourne" of the testes of the common Earthworm, and a number of subsequent researches, particularly those of Dr. R. S. Bergh 6, have firmly established the exactness of Hering's statements. With regard to exotic genera of Lumbricidae, how ever, our knowledge is still very imperfect. The fact that the so-called "testes" are, in the majority of forms, apparently unconnected with the funnels of the vasa deferentia, and the frequently racemose structure of the former bodies, has probably influenced those writers who have (in m y opinion erroneously) described the vesiculae seminales as "testes." Br. Horst appears to be tbe first who has noticed the true testes in any post-clitellian or intraclitellian Earthworms; in his account of the anatomy of Perichata 1 It is quite impossible to regard this body as a receptaculum, containing as it does indifferent cells, unless it be admitted that the receptaculum coincides in position with the ovary, as in the case of the testes and vesiculae; in this case the, continuity of the duct and the sac which envelops the ovary will have to be regarded as secondary. I a m quite disposed to regard this as a possible view, but it does not affect tbe anatomical fact of the continuity of the ovary and its duct in the adult condition. 2 " Contributions to Morphologv. lchthyopsida.-No. 2. O n the Oviducts of Osmerus ; with Eemarks on the Eelations of the Teleostean with the Ganoid Fishes," P. Z. S. 1883, p. 132. 3 Zool. Auzeig. Bd. viii. p. 181. * Zeitschr. f. wiss. Zool. Bd. viii. (1852). 5 Quoted bv J. E. Bloomfield, Quart. Journ. Micr. Sci. 1880. « Zeitschr. f. wiss. Zool. 1886; Zool. Anzeig. 1886, p. 231. |
