IO 



K. MITSUKURI. 



every year as that year s crop. There may therefore be seen some of the 

 next year's crop already produced as delicate and slender tubes in front 

 of the enlarged and fully-grown tubes of a given year. This suspicion of 

 mine has been confirmed by a recent paper by 

 THEEL*, and I would urge that what he sees in 

 Mesothuria intestinalis is not an exceptional case, so 

 far as regards the crops of the reproductive tubes 

 in successive years but is what takes place 

 normally in all the Holothurians. 



When the generative elements 

 have been shed from a tube, the 

 reproductive cells which are left 

 in it undergo degeneration. 

 If individuals caught in 

 August or September are 

 opened, the reproduc- 

 tive tubes which 

 are much more 

 slender and small- 

 er than during 

 the spawning 

 season and are 

 evidently shrink- 

 ing, have a 

 peculiar exhaust- 

 ed appearance, 

 not to be mis- 

 taken for young growing tubes, and aie moreover dark in color, 

 owing to the pigment which has appeared with the process of 

 degeneration. It is my belief that these tubes never again enlarge 



Fig. 2. — A rift spermatic 

 iubc. X g. 



* A Remarkable Case of Hermaphroditism in Holotliurids. Hihang till K. Svenska Vet.- 

 Akad. Handlingar. Bd. 27. Afd. IV. No. fi. 



