92 STUDIES IN LIFE AND SENSE. 



a double series of suckers." The two " proboscides " of Aristotle 

 are the " tentacles " of the modern naturalist ; and Pliny, speaking 

 of the uses of these tentacles, remarks that they may be used for the 

 capture of prey at a distance, or may be employed to anchor their 

 possessors safely amid the boisterous waters. The " suckers " (fig. 6, A), 

 which constitute a most noteworthy armament of 

 the arms, are borne on short stalks in the ten- 

 armed cuttlefishes, but are unstalked in the 

 eight-armed species. Each sucker (fig. 6, B) ex- 

 hibits all the structures incidental to an appa- 

 ratus adapted to secure effective and instan- 

 taneous adhesion to any surface. It consists of 

 a horny or cartilaginous cup (a), within which are 

 muscular fibres converging towards its centre, 

 where they form a well-defined plug or piston (b\ 

 By tlie withdrawal of this plug a partial vacuum 

 is produced, and the suckers adhere by atmo- 

 spheric pressure to the surface on which they are 

 placed. The sucker is released by the projection 

 of the plug and by the consequent destruction of 

 FIG. 6. SUCKERS OF t j ie vacuum. The number of the suckers varies, 



THE CUTTLEFISH. , . , . , , , ,, 



but is always considerable ; and when we reflect 

 that the array of suckers can be instantaneously applied, and that 

 their hold is automatically perfect, the grasp of the cephalopods is 

 seen to be of the most efficient kind. In some cuttlefishes, and most 

 notably in the so-called "hooked squids" (Onychoteulhis), the pistons 

 of the suckers are developed to form powerful hooks, by means of 

 which the prey may be secured with additional facility ; and in the 

 common squids the margin of the sucker is provided with a series 

 of minute horny hooks. The " arms " themselves, it need hardly be 

 remarked, are extremely mobile ; they are highly muscular, and can 

 be adapted with ease to the varied functions of prehension and 

 movement they are destined to subserve. As regards their arrange- 

 ment, they are arranged in four pairs a dorsal and a ventral pair, 

 and two lateral pairs ; the two elongated tentacles, when developed, 

 being situated between the third and fourth pairs of arms on the 

 ventral or lower surface. 



The systematic examination of any single animal form, or of any 

 one group of animals, resolves itself into a consideration of the 

 various systems of organs whereby the work (or physiology) of the 

 being or beings is carried on. Primarily, the scientific pathway con- 

 ducts us to the animal commissariat or alimentary system as a fair 

 starting-point ; thence to the blood-circulating system ; thirdly, to 

 the excretory apparatus, consisting of the breathing organs, kidneys, 

 and like glands ; fourthly, to the nervous apparatus, exercising the 



