OCR Text |
Show 824 MR. F. E. BEDDARD ON [Nov. 3, the gland, and which may be regarded as its duct, is hypertrophied compared to what it is in Lumbricus. In the dorsal series of nephridia this muscular duct is extremely long, and before perforating the body-wall it gives off a minute caecum which extends beyond (dorsal to) the external orifice ; in the most anterior segments of the body this diverticulum is not present (Plate LII. fig. 4). In the ventral series of nephridia the terminal muscular duct is very short, but it is connected with, and opens into, a large sac-like diverticulum (Plate LII. fig. 5) about equal in length to the muscular duct of the dorsal nephridia, and which lies, not beyond the setse, but on the same side of them as the nephridium itself. The differences above indicated are absolutely distinctive of the two series of nephridia : wherever these organs opened by the ventral pair of setse they were found to have a large diverticulum developed at the expense of the terminal duct, which is in consequence short; wherever they opened by the dorsal pair of setse, the muscular duct was long, the csecum short, projecting on to the further side of the setse. § Generative Apparatus. The male generative apparatus of A. nova zelandia as well as the other two species consists of two pairs of testes, two pairs of vasa deferentia, with which are connected a prostatic gland and a number of peculiarly modified setse. The position of the several glands and their ducts are shown in the accompanying drawing (fig. 3, p. 825). The testes are situated in segments 11 and 12, and have the form of racemose glands composed of a number of spherical acini. When the body is opened the testes are seen to extend above the dorsal vessel but are not united together ; the testis of each side is free from its fellow ; they are attached by a stalk to the anterior mesentery of the segment which they occupy ; in the tenth and eleventh segments are the funnels of the vasa deferentia ; the pair of funnels of each segment are close together on either side of the median line and just above the nerve-cord; the margins of the funnel are extremely folded and complicated, which renders their detection a matter of great ease ; it is rather curious to find that the anterior pair of funnels are situated in the segment in front of that which contains the anterior pair of testes, but a similar condition has been recorded in other Earthworms. It must be noted that the funnels of the vasa deferentia are entirely independent of the testes ; they project freely into the interior of their respective segments, and there is no possibility of regarding the testes as an expanded portion of the true funnel of the vasa deferentia. The testes therefore in this Earthworm are the real sexual glands and are not the homo-logues of the so-called " testes" of Lumbricus, which are merely the dilated ends of the vas-deferens funnels. As is well known, the real testes of the common Earthworm are four minute bodies, which discharge their contents into the sac-like termination of the vasa deferentia, and seem to disappear when the animal is mature; it is |