1387.] ANATOMY OF EARTHWORMS. 3"9 



brought about. Tlie 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 ifec' 



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. 

 Tliere is therefore a difference between Eudrilns and other Lumbri- 

 cidfe, like that "hich exists between Lepidosteus and many Tele- 

 osteans on the one hand, and Osmerus and Amia on the other ^. It 

 may also be remarked that, at any rate in this particular, it is 

 impossible to draw a hard-and-fast line between the 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 suppo-ed to be an outgrowth or con- 

 tinuation of the gland itself. Recently Nussbaum'' has stated that 

 the reproductive organs in certain Hirudinea are developed indepen- 

 dently of their ducts, which have a resemblance to iiephridia. 



It is plain therefore that in this case, at any rate, the distinction 

 betwee:! tubidar and other ovaries falls to the ground. It is inter- 

 esting to note that the condition which is characteristic of the Leech 

 may also occur in a Chaetopod. 



Male Generative Apparatus. — In spite of tiie fact that Hering * 

 clearly demonstrated the true testes of Lumbricus, and distinguished 

 them from the vesioulae 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 ", have firmly estab- 

 lished the exactness of Heriug's statements. With regard to exotic 

 genera of Lumbricidse, however, 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 racemo-e structure of the former bodies, has probably 

 influenced those writers who have (in my opinion erroneously) de- 

 scribed the vesiculse seminales as "testes." Dr. Horst appears to be 

 the first who has noticed the true testes in any post-clitellian or intia- 

 clitellian Earthworms ; in his account of the anatomy of Ftrickcefa 



^ It is quite impossible to regard tliis 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 vesiculse ; in this 

 case the continuity of the duct and the sac which en-velops the ovary will ha>e 

 to be regarded as secondary. I am quite disposed to regard this as a possible 

 view, but it does not affect the anatomical fact of the continuity of the ovary 

 and its duct in the adult condition. 



' " Contributions to Morphology. Ichthyopsida. — No. 2. On the Oviducts of 

 Oameritx ; with Eemarks on the Eelations of tiie Teleostean with the Ganoid 

 Fishes," P. Z. S. 1883, p. 132. 



^ Zool. Aiizeig. Bd. viii. p. 181. 



♦ Zeitschr. f. wiss. Zool. Bd. viii. (1852). 



^ Quoted bv J. E. Bloomfield, Quart. Journ. Micr. Sci. 1880. 



^ Zeitschr. "f. wiss. Zool. 1886; Zool. Anzeig. i88R, p. 231. 



