HOLOTHURIA. 45 



Future observers may discover the genuine functions of these or- 

 gans which are at present very doubtful. All the authors whose words I 

 have in recollection, except the Neapolitan professor, assign a tentacular 

 office, or what is equivalent to feeling in the larger animals, as their 

 nature, while he conjoins something respiratory along with it.* To 

 this, however, as will afterwards appear, there are certain relevant ob- 

 jections. Nevertheless, the opinion of so learned and industrious a na- 

 turalist merits high consideration. 



During quiescence of the Holothuria, the tentacula occupy the nar- 

 row circumferential channels of the cyhnder, which is retracted within 

 the cavity of the body. Their display is extremely irregular, and is 

 often so transient that it may seem quite capricious — nor essential to 

 the necessities of the animal. A specimen obtained in June, floated as 

 if turgid with v.ater. The tentacula sometimes protruded hke a purple 

 plume, along with some part of the cylinder. But they were never seen 

 completely expanded until the subsequent March, that is, for nine 

 months. This specimen afterwards displayed them occasionally during 

 the whole day in full vigour, — an incident which occurs very rarely. 

 Another specimen procured in December, was not observed to display 

 the tentacula before the end of March. These two specimens sometimes 

 assumed the form of a horse-shoe, when the two ends, from the great 

 curvature of the body, came almost in contact. 



The destruction of any resisting prey is irreconcileable with the ex- 

 traordinary timidity of this creature. It is firmly rivetted to the spot 

 of its selection by numerous suckers, which, in the present instance, 

 constitute the shaggy coat investing it. An adhesive faculty also at- 

 taches shells or fuci to the whole body, when coming in contact. All 

 this is spontaneous, but sooner than quit its hold by violence, the Holo- 

 thuria will submit to the severest injuries, even to absolute destruction. 

 Thence may be understood the difficulty of obtaining specimens entii'e. 

 . Were it bold and oamivorous, the same powerful adhesion might enable 



* Delle Chiaie's Observations were made on a species ilifterent fi'om mine. After 

 describing the internal respiratory organs connected with the intestinal canal, he says, 

 " the tentacula are also the medium of the respiration of these admirable beings," § 4. 



