VERMES GENITAL OR( L 1 .V,S 



263 



masses between the branches of the intestine, especially on the dorsal 

 side. These masses of eggs are regarded as ovaries. It is, however, 

 possible that they consist of eggs which have left the real ovaria. 



da 



genital 



FIG. 176. Section through Myzostoma, after v. Graff, ov, Ovaries ; da, intestinal branches ; 

 !t, uterus ; dm,, dorso-ventral muscle fibres ; sn, suckers ; h, testes ; qm, transverse muscles ; Im, 

 ventral gaiiglionic masses ; pa, parenchyma ; md, intestine. 



The origin and places of formation of the eggs are not known with any 

 certainty. The ripe eggs pass into a spacious uterus which lies on the 

 dorsal side of the stomach -intestine. One dorsal and two lateral 

 oviducts connect the uterus with the cloaca. The male 

 apparatus is paired. On each side 

 branched solid testicle strands 

 lie in the parenchyma below the 

 intestine and its branchings. On 

 each side an anterior and a pos- 

 terior vas deferens collect the 

 sperm from the testes. Both 

 vasa deferentia enter a muscular 

 lateral sperm vesicle, which lies 

 between the 3d and 4th suckers, 

 and which opens outwardly at the 

 edge of the body. 



Prosopygia. The places of 

 formation for the eggs and sperma- 

 tozoa of the Sipunculidce, Phoron- 

 i<li.i', and Brachiopoda are definite 

 points of the endothelium of the 

 body cavity. The sexual products 

 fall into the ccelomic fluid, and 

 are emptied out thence by the 

 nephridia, as Avas the case in the 

 Polych?eta. 



In the Sipunculidce the formation of 

 the germs takes place for the most part 

 at the base of the ventral proboscis 

 retractors. Phoronis is hermaphrodite. 



FIG. 177. Diagrammatic representation of 

 the organisation of a Brachiopod, from the dor- 

 sal side ; the dorsal halves of shell and mantle are 

 removed. , Arms ; ink, mantle cavity ; m, nn >uth ; 

 !, liver; ma, stomach; n, nephridia; an, anus; 

 !/, genital glands ; rs, part of the ventral shell 

 which projects backwards over the dorsal shell ; 

 r, anterior; h, posterior; /, right; I, left. 



The male and female sexual products arise 



