32 



AN ELEMENTARY TEXT-BOOK OF BIOLOGY. 



I) 



fluid, in which are numerous highly refracting granules. The 



presence of guanin (C 5 H 5 N 5 O) has been proved. 



4. Keproductive Organs (Fig, 7). Distoma is hermaphrodite, 



and its very complex reproductive organs lie, for the most part, 



ventral to the intestine. The 

 genital aperture (Fig. 6, g.o) is a 

 small oval pore situated in the 

 middle line between the anterior 

 and ventral suckers, and rather 

 nearer the latter. It leads into 

 a shallow pit, the genital sinus (Fig. 

 6, B), on the right of which is the 

 larger male aperture (c/), and on 

 the left the female aperture (od'). 



(1) The Male Organs consist 

 of two spermaries (testes) (T), one 

 behind the other, extending over 

 a considerable area in the middle 

 region of the body. Each is made 

 up of several much-branched tubes, 

 which unite to form a tube or duct 

 of smaller calibre, the spermiduct 

 (vas deferens). The spermiducts 

 run forwards, one on each side of 

 the middle line, to the level of 

 the ventral sucker (S). In the 

 latter part of their course they 

 converge (Fig. 6, B, B'), and at the 

 above level open into a spindle- 

 shaped thick - walled tube, the 

 vesicula seminalis (v. sm\ which 

 tapers into a very delicate con- 

 voluted tube, the ejaculatory duct 

 (ej.d), that again opens into a 

 shorter and stouter tube, the penis 

 (cirrus) (cr), opening at the male 

 aperture. Around the end of the 

 ejaculatory duct a mass of nucle- 

 ated cells is arranged, each of which 



opens by an excessively fine tube into the duct. They are the 



unicellular accessory glands (ac.gl). 



Do 



Fig. 7. DISTOMA HEPATICUM 

 (from Claim after Sommer). O, 

 Mouth ; D, limb of intestine ; S, 

 ventral sucker, in front of which 

 is genital opening ; T, testis, in 

 front of which is the rounded 

 shell - gland ; Do, yolk - gland ; 

 Ov, oviduct ; Dr, ovary. 



