134 Description,'^ of Frejjci rations. 



glandular tissue, and is called consequently the prostatic part of 

 the male intromittent apparatus; the mesial siphon-shaped tube 

 re])resenting- a penis, and the lateral ducts being ductus ejaculatorii. 

 Tracing the vas deferens of the right side outwards, we see that it 

 passes under the nerve cord, to join a convoluted epididymis-like 

 mass of a yellowish colour, which from its contents appears to be 

 analogous to a vesicula seminalis. A slightly tortuous duct enters 

 the organ from behind forwards, after receiving on its inner side 

 the short transverse ducts passing to it from each of the nine 

 globular testes which are seen close to the nerve cord, arranged 

 one in each of nine segments, beginning with the one next but 

 one in order to that in which the convoluted vesicula seminalis 

 is lodged. The female generative apparatus is lodged in the seg- 

 ment interposed between that which contains the first testis and 

 that which contains the vesicula seminalis ; and four secondary 

 annuli are seen to be interposed externally between those in which 

 the outlets of the two sets of generative organs are pierced. The 

 vagina has the form of an oval sac with thick muscular walls. 

 From its apex a single tortuous oviduct arises which has its coils 

 enveloped in loose tissue, the microscopic elements of which furnish 

 us with large and beautiful specimens of unicellular glands dis- 

 charging their secretion by isolated ducts. The oviduct divides 

 into branches, one of which is seen passing under the nerve cord, 

 on the apices of which the ovaries are carried. Externally to the 

 line of the vasa deferentia and alternating in position with the 

 testes, we see a row of globular sacs only a verj^ little less in size 

 than these organs. These sacs communicate with the exterior 

 by the orifices already spoken of, Prep. 39, p. 127, as marking 

 the posterior limit of each of the primary segments of the body. 

 Exteriorly to each of these sacs we see a loop-shaped gland, the 

 outer convex end of which is directed upwards, and in the natural 

 condition of the parts almost vertically so, whilst internally it is 

 connected with the globular sac by a short duct passing from the 

 anterior limb of the loop backwards; and in the region of the 

 testes has a coecal process prolonged on to each of those organs. 

 The connection which subsists in the Lumbricidae between the 

 open mouth of a modified segmental organ and the reproductive 

 glands, may be regarded as represented in the Leech by the ar- 

 rangement just described. There are eight of these segmental 



