VERMES— GENITAL ORGANS 



257 



the posterior part of the uterus ; this is connected with the atrium, 

 and during copulation becomes filled with spermatozoa. In the male 

 genital apparatus the actual testes have not yet been found. The 

 other parts correspond with the various divisions of the female appar- 

 atus. AVe can distinguish sperm sacs (corresponding with the uteri 

 of the female), sperm duets, and the well-developed eloaea, a flask- 

 shaped organ whose terminal part can be evaginated. There is no 

 organ corresponding with the receptaculum of the female. 



3. Aeanthoeephala ; Female Apparatus (Fig. 171). — In quite 

 young animals the ovaries are enclosed in the ligament by means of 

 which the genital apparatus is suspended 

 from the base of the proboscis sheath. < 

 Masses of eggs (swimming ovaries) early i, 

 reach the body cavity, probably by the 

 bursting of the ligament, and in sexually 

 mature animals are there present in great 

 numbers together with single detached eggs. 

 From the body cavity they are transmitted 

 to the exterior by a muscular apparatus 

 which is of very comijlicated structure, 

 although consisting of a limited, but for 

 each species definite and constant, number 

 of muscle cells. We distinguish in it first 

 an apparatus for swallowing the ova, the 

 uterus bell, to the bottom of which the 

 posterior end of the ligament is attached. 

 It is in open communication with the body 

 cavity by means of a large anterior and 

 a small posterior aperture. It alternately 

 expands and contracts, and thus draws in 

 the eggs which float in the coslomic fluid. 

 From the uterus bell the eggs piass into 

 the anterior apertures of two short canals 



which are called oviducts. The oviducts p.^. m.-remale genital appar- 



emerge into a tubular unpaired division, atus of an Echinorhynciius, dia- 

 the uterus, and this opens externally at gi-ammatic. ug, uterus ten. vog, 



,, ,. tj:j_iiii ij_ anterior aperture of the same ; hog, 



the posterior end of the body by a short posterior ditto;.™;, anterior aperture 



terminal piece, the vagina. Through the of one of the two oviducts (od) ; «, 



posterior aperture of the uterus bell the ii^rus ; ^, vagina ; ™, female aper- 

 ^. 1-11 1 1 - -1 ture ; 0, ovaries ; li, ligament. The 



unripe eggs which have been drawn m with arrows indicate tlie course talten by 



the others are returned to the body cavity, the eggs in passing from the tody 



Male Apparatus (Fig. 172, p. 258).— -^^^ity to the exterior. 

 Two, or less frequently three, testes lie in the ligament. Each is 

 continued in the form of a sperm duet. Each of these sperm ducts 

 has three pouch-like invaginations along its course (sperm vesicles). 

 Posteriorly they unite to form one common muscular vas deferens, 

 which enters the bursa at the point of a conical muscular projecting 

 VOL. I s 



