CUTTLE-FISHES. 



223 



of holding their prey, are exceedingly destructive to fishes and 

 Crustaceans around our coasts. 



Their prehensile arms are, in the greater number of species, 

 provided with suckers, called " acc- 

 tabula" that act like cupping-glasses. 

 The mechanism for producing adhe- 

 sion by means of these wonderful 

 organs is extremely curious. From 

 the margin of each cup muscular 

 fibres converge towards the centre, 

 at a short distance from which they 

 leave a circular aperture ; behind this 

 is a false floor that can be raised like 

 the piston of a syringe, and thus pro- 

 duce a complete vacuum within the 

 cup. So perfect is this mechanism 

 that, while the piston continues raised, 

 it is easier to tear away the sucker 

 from the arm than to release its hold, 

 but as soon as the muscular effort 

 raising the piston ceases, the vacuum 

 produced by its retraction is in an 

 instant destroyed, and all the suckers 

 detach themselves.* 



Few spectacles are more wonderful than that presented "by 

 these animals, while alive and free in their native element : 

 changing their colours with the rapidity of thought, they dart 

 from place to place with amazing activity ; some species, indeed, 

 cleave the water with such rapidity that the eye can scarcely 

 follow their movements. Sometimes they swim by means of 

 vigorous flappings of their arms, which are webbed like the feet 

 of swans. Sometimes they employ their fleshy fins, or else pro- 

 pel themselves backward by forcible and repeated ejaculations of 

 water through the tube or siphon placed in front of their bodies. 



* The tenacity of the grip of the Cephalopod was fully npprec;ated by Homer, but 

 the beauty of his simile has been but little understood by his translators": 

 " As when the cuttle-fish enforced forsakes 

 His rough abode, with his adhesive cups 

 He gripes the pebbles still ; 

 So he, Ulysses, with his lacerated grasp 

 The crumbled stone retained, when from his hold 

 The huge wave forced him, and he sank again." 



HOMER'S "Odyssey" Book V. 



FIG. 238. STRI- CTURE OF SUCKERS 



OF C'L'TTLE-FlSH. 



