280 Mr. E. A. Minchin on the 



the preceding section. The ninth section (not figured) was 

 almost precisely similar to the eighth. In all the sections the 

 delicate right respiratory tree has been lost, having been 

 probably torn a\Yay by the razor. 



The conclusion I draw from these preparations is as 

 follows : — Tlie Cuvierian organs, after commencing to elon- 

 gate within the body in the manner described above, are in 

 some way directed to the dorsal wall of the cloaca, which 

 they break through. It may be that the powerful contrac- 

 tion of the body- walls, compressing the liquid contained in 

 the coelonie, causes the wall of the body-cavity to break at 

 its weakest point, which is presumably the dorsal wall of the 

 cloaca, through which the organs are then forced. Bell has 

 also observed Cuvierian organs in the cloaca of one of his 

 specimens of tliis form (1, p. 375). They thus reach the 

 anus, from which they issue point foremost, to elongate in 

 the surrounding water. I have frequently found that pieces 

 of the cloacal wall, recognizable by their radiating muscles, 

 are ejected with the organs, and have no doubt that the 

 aperture in the cloaca tln-ough which they escape is tempo- 

 rary. An interesting experiment would be to stimulate a 

 Holothurian to eject its Cuvierian organs after first ligaturing 

 the anus, so that they would be unable to escape by the usual 

 path, and would be obliged either to find some other mode of 

 exit or remain within the body-cavity. 



4. Inunction of the Cuvierian Organs. — The greater number 

 of authors consider them as organs of defence. Peach (6, 

 p. 173) described in 1845 how the animal "is extremely 

 irritable, and on being touched or disturbed throws out a 

 bunch of white tapered threads about an inch in length and 

 one eighth in thickness ; these soon become attenuated, 

 either by the agitation of the water or the coming into contact 

 with something ; they stick to everything they touch, and 

 from that the animals are called ' cotton- spinners ' by the 

 fishermen." Ludwig, in his magnificent work ' Echino- 

 dermata ' (5, p. 401 ef seq.), sums up the views of different 

 authors and inclines to the view that they are organs of 

 defence, though a little uncertain as to whether that is their 

 primitive function, owing to the statements of Herouard. 

 Cuenot also argues strongly that they are a means of defence 

 (2, p. 372 et seq.) . Herouard alone of recent writers expresses 

 his views to the contrary in the following words (3, p. 673) : — 

 " Les tubes de Cuvier sont considerds actuellement comme 

 ^tant des organes de defense. Partisans des causes finales, 

 les auteurs ont attribue a ces organes de telles fonctions, 

 parce qu'ils adherent remarquablement aux objets qui les 



