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Show 3S0 MR. F. E. BEDDARD ON THE [_Apr- 19. indica 1 this naturalist plainly perceived that the structure of the male generative glands in Penchata was essentially similar to that of Lumbricus. Mr. Benham2 was also able to discover the true testes iu Microchata, situated on the anterior wall of the segments which contain them, and enclosed in a common sac with the vesiculae seminales aud the terminal funnels of the vasa deferentia. More recently Dr. Bergh3 has given a full account of the male reproductive orgaus of Perichata, which establishes without any doubt the correctness of Horst's observations. Iu Eudrilus there are three pairs of white glandular-looking bodies in segments 10, 11, and 12, which evidently correspond to the structures termed testes by Perrier in his notes on the anatomy of this genus 4. In the dissected worm these bodies were very friable ; and for that reason I have found it impossible to give an accurate idea of their naked-eye appearances. These bodies are not testes, but vesiculae seminales ; their structure resembles that of the vesiculae seminales of Lumbricus (fig. 11, a); they consist of a delicate fibrous network of trabeculae, in the compartments of which are lodged the developing spermatozoa. In the case of the two anterior pairs of vesiculae seminales, the fibrous sheath of the organ was found to contain (fig. 2, t) a small irregularly-shaped body composed of small uniformly-sized cells ; these bodies were attached firmly to the ensheathing fibrous tunic, and at one point tbe fibrous tunic was seen to be continuous with the intersegmental septum close to the nerve-cord ; and here the cellular body appeared to be attached also to the mesentery. These two pairs of orgaus seem to be without doubt the true testes. Their position, attached to the anterior wall of segments 10 and 11, as well as their enclosure by the tunic of the vesiculae seminales, is entirely in favour of such an identification. In both the I 0th and llth segments the vesiculae seminales were united by a median unpaired region, lying beneath the alimentary tract and enclosing the ventral blood-vessel, but not tbe nerve-cord; it is with this portion of the vesiculae that the funnels of the vasa deferentia are connected, as will be described shortly. In the case of the anterior pair of vesiculae this median region was closely packed with bundles of developing spermatozoa ; the median region of the llth segment, on the contrary, was nearly empty of developing spermatozoa. The two vesicula? of the 12th segment do not enclose any testis; they appear to be unconnected with the vesiculae of the two anterior segments ; they are in all probability, however, to be regarded as outgrowths of the latter, and not as constituting an independent third pair of vcsiculos. It is important to notice that Eudrilus, although so abnormal in the structure of the female generative apparatus, conforms to the ordinary type in the structure of the male generative organs. The facts detailed above, coupled with the researches of Horst, Benham, 1 Niederl. Archiv f. Zool. Bd. iv. (1877-78). 2 Quart. Journ. Micr. Sci. vol. xxvi. (new series.) 3 Loc. cit. 4 loc. cit. |
