Nov. 9, 1888.] 



SCIENTIFIC NEWS. 



483 



statural fgfatorg* 



NATURAL SUCKERS. 

 Although we do not meet with it among the mammals 

 or the birds, the sucker in some of the lower forms 

 of life is of considerable importance, not only in 

 the capacity of a weapon, but also in that of an 

 organ of locomotion, as well as of a means by which 

 locomotion may be checked. Thus, to adduce but one 

 example in illustration of each method of employment, 

 the suckers of the cuttle-fish are weapons of offence, 



air-pump, the more powerful and effective by reason of 

 its employment under water. And all these manifold 

 suckers are entirely under the control of their owner. 

 The principle upon which they are constructed is very 

 simple. " The adhesive disc itself," says Rymer Jones, 

 " is composed of a muscular membrane, its circumference 

 being thick and fleshy, and in many species supported 

 by a cartilaginous circlet, so that it can be applied most 

 accurately to any foreign body. In the centre of the 

 fleshy membrane is an aperture leading into a deep 

 cavity, at the bottom of which is placed a prominent 

 piston, which may be retracted by muscular fibres pro- 



Gecko. 



those ot the gecko render possible the employment of 

 the limbs under unusual circumstances, while a similar 

 organ in the gobies serves as an anchor, by means of 

 which its possessor may defy the fury of the waves. 

 And in each of these cases the construction of the sucker, 

 and of the apparatus connected with it, is well worthy 

 of examination. 



Let us take, in the first place, the tentacles of the com- 

 mon octopus, or poulpe, by means of which it seizes its 

 victims, and drags them closely and more closely to its 

 body, until its strong curved beak can be plunged into 

 their flesh. Each of these tentacles is studded with an 

 array of no less than one hundred and twenty pairs of 

 suckers, every one of which constitutes a most perfect 



vided for the purpose. No sooner, therefore, is the cir- 

 cumference of the disc placed in close and air-tight con- 

 tact with the surface of an object, than the muscular 

 piston is strongly drawn inwards, and, a vacuum being 

 thus produced, the adhesion of the sucker is rendered as 

 firm as mechanism can make it." 



In some of these singular animals the ordinary 

 suckers, powerful as they are, do not seem to be suffi- 

 cient, and are reinforced by others of a different character, 

 situated upon two additional tentacles. Each of these 

 bears a strong and sharp hook, which is forced deeply 

 into the flesh of the victim by the mere pressure of the 

 sucking-disc, and thus the sucker practically consists of 

 two wholly distinct weapons, each of a highly formidable 



