Cuvierian O/'^/a^Js o/'llolotliuria nigra. 2S3 



Tlie above theory of tlic luuctioii and origin of tlie 

 Cuvierian organs is, I am well aware, an hypothesis only, and 

 requires much more foundation before it can be accepted. 

 Nevertheless, on the principle that the test of an hypothesis is 

 its power of explaining facts, 1 venture to bring it forward as 

 a suggestion as to the true nature and homologies of these 

 very curious and interesting organs. 



Oxford, 

 Julv 1892. 



List of Worlcs cited in the Text. 



1. Bkll, F. Jeffrey. — " Stiulie.s in the llolothiirioidea. — IV. Ou tlie 



Structural Characters of the Cottoii-Spiuner {lluUitlniria niijra), 

 and especially of its Cuvierian (.)rf,'aiis." " V. Further Notes on 

 the Cotton-Spinner." Proc. Zool. Soc. 1884, pp. 372-37(5 and 

 pp. 5G3-5U5. 



2. CuENOT, L. — '' Ltudes luorphologiques sur les EchinoJernies." Arch. 



de Biol, tome xi. fasc. 3 and 4, pp. 313-080. 



3. IIkrouaud. — " llecherches sur les Holothuries des Cotes de France." 



Arch, de Zool. e.^p^r. et g6u. (2) t. vii., 1889, pp. 535 et seq. 



4. JouHPAN. — " Recherches sur rilistologie des Holothuries." Ann. (hi 



Musee d Hist. Nat. de MarseiUe, tome i., Mem. no. 0. 



5. LuDWiG, H. — Echinoderniala, in I^u'onu's ' Khssen uud OrJnungen 



des Thierreichs,' Band ii. Abth. 3. 



6. Peach, C. W.— " On the ' Nij,^ger ' or ' Cotton-Spinner ' of tlie Cornish 



Fishermen."' Ann. & Ma<^-. Nat. Ilist. vol. xv. l84-">, pp. 171-174. 



7. Sempku, C. — " Reisen im Archipel der Philippini'n." II. Tlieil, 



Wissenschaftliche Resultiite, 1 Band, Ilolothurien. Leipzij,--, 



18o8. 



EXPLANATION OP PLATE XVII. 



F!(j!i. 1 a k h. Two Cuvierian orphans as .seen during the process of elon- 

 gation and production of the sticky thread. /*, "head'' or 

 reniai'.is of the original organ, which is being used up to form 

 the thread (thr.) nt the point ,c. 1 h is drawn from an orgnn 

 which had gone off on being placed in Kk-ineiiberg's picric. 

 Natural size. 



ln(j>i. 2-8. Seven .sections taken from a series of nine thick sections through 

 the posterior end of a llolutlmrian which had commenced to 

 eject its Cuvieiiiui organs on being ])laced bodily in spirit. 

 Represented somewhat diagrar.imalically and slightly enlarged. 

 Lettering for all the fig-ures: — ^7^/., integument ; /.?«., longitu- 

 dinal muscles; c/., cloaca; c.o., Cuvierian organs; Lmj)., left 

 respiratory tree; v., rectum. 



J-\\(j. U re))iesents the posterior ])art of a specimen of Holothuria nigra, 

 opened while in the act of rejecting some of its Cuvierian 



