FISHES. 39 



the testes runs the vas deferens, and the two unite to form a common 

 canal, longer or shorter, which joins the urethra, and thus opens in 

 a groove or on a papilla behind the anus 1 . In most osseous fishes 

 the tissue of the testes consists of tubes, of which the blind extremi- 

 ties are directed towards the outside of the organs, sometimes 

 dividing there into two branches, and open on the inside into the 

 efferent vessel 2 . In the eels 3 and in Petromyzon, on the other hand, 

 the testes are flat bands like the ovaria, of a granular tissue. 

 Efferent ducts are absent ; the seed is received by the abdominal 

 cavity and escapes by an aperture behind the vent. In the Plagio- 

 stomes the testes are of a vesicular tissue, and in these vesicles 

 granules are contained which are filled with sperma. Fine ducts 

 (vasa efferentia) run to the epididymes, situated behind the testes, 

 and from these arise the two efferent vessels, at first very tortuous, 

 afterwards straighter, which run over the kidneys and finally 

 widen into two vesiculce seminales, which are supplied internally 

 with annular partitions. From these the seminal fluid is conducted 

 to the penis, which lies in the cloaca. There are, in addition, 

 behind the pelvis, near the tail, appendages which are supported 

 internally by cartilage ; they serve to embrace the female during 

 copulation by affixing themselves to her tail 4 . 



Most osseous fishes do not copulate, but the males sprinkle the 

 eggs laid by the female with their seminal fluid. It is probable that 



1 See a figure of the testes in Trigla lyra in the Tabula of CARUS cited above, Fasc. 

 v. Tab. IV. fig. 4. 



2 This tubular structure, first observed by RATHKE, was afterwards more fully 

 illustrated by TREVIRANUS and J. MUELLER. See TREVIRANUS Zeitsckr. fur Physiol. 

 ii. Darmstadt, 1827, s. 10 13, Tab. in. fig. 4, MUELLER Depenitiori glandular, struct. 

 p. 104, Tab. xv. fig. 8. 



3 According to SCHLUESSER, it is not improbable that the parts described by HOHN- 

 BAUM-HORNSCHUCH as testes in eels, are only undeveloped ovaria, and that male eels 

 are still unknown. Gr. SCHLUESSER de Petromyzontum et AnguUlarum, Sexu. Diss. 

 inaug. Dorpati, 1848. 



4 Compare TREVIRANUS Ueber die Zeugungsorgane des Dorrihay, Zeitschr. fur 

 Physiol. n. 1827, s. 3 10, Tab. in.; STANNIUS in MUELLER'S Archiv, 1840, s. 41 

 43. On the sexual organs of fishes consult especially RATHKE Beitr. zur Gesch. der 

 Thierwelt,iiQ Abth. s. 117 206, and in MUELLER'S Archiv, 1836, s. 171 186, and on 

 the development of these parts, Beitr. zur Gesch. der Thierw., 3teAbth. s. i 18. Also 

 J. MUELLER Ueber den Tcornigen Ban der Hoden lei mekreren Fischen, in TIEDEMANN 

 and TREVIRANUS Zeitsckr. f. Physiol. iv. 1831, s. 100113, and H. STANNIUS Ueber 

 di mdnnliche Geschlechtstheile der Rochenu. ffaien, MUELLER'S Archiv, 1840, s. 41 43. 



