BIHANG TILL K. SV. VET -AKAD. HANDL. BAND 27. AFD. lY. N:0 6. 35 



Siimmary. 



1. Mesothuria intcstinalis (xVscan.) is a heriuaphrodite. 



2. Tliis hermapbrodism differs from that known in other Holothu- 



rids, the male and female products reaching their maturation 

 in different, successive series of genital tubes. 



3. Tbe genital tubes are subjected to a successive destruction and 



atrophy, from bebind in a forward direction. 



4. Marks of former genital tubes in tbe shape of maculse, protu- 



berances and slightly brancbed processes are seen on the poster- 

 ior portion of the genital basis. 



5. The genital tubes are supplied anteriorly, a coutinual growth of 



new ones taking place from the anterior portion of the geni- 

 tal basis wbere it communicates with the efferent duct and the 

 "gerrainal cord." 



6. The "gerrainal cord" is a direct band-like continuation of the 



genital basis, running along the left side of the efferent duct. 



7. The genital basis, with its tubes and their sexual contents, is 



continually renewed from the gerrainal cord. 



8. The genital basis gradually changes, its posterior end being suc- 



cessively obliterated. 

 'j. The glands of Bördas are no secernating glands hut huds of 

 future genital tubes. 



10. During the growth and maturation of the ova and sperraatozoa, 



the longitudinal folds of the genital tubes at first becorae very 

 volurainous; they gradually decrease, forming finally very in- 

 considerable ridges. This is due to the afflux and deflux of 

 blood. 



11. The eggs may be destroyed by wander-ceUs icith vacuoles. 



12. The posterior end of the genital basis becoraes absorbed by wcui- 



der-cells icilh spheres. 



13. IJundles of very fine (nervous?) filaraents cross the ratber wide 



interstices between the bases of the coluranar ciliatcd epithe- 

 lial cells which invest the cavities of the genital basis and the 

 efferent duct. 



