106 



HARDWICKE'S SCIENCE-GOSSIP. 



[May 1, 1869. 



macerated into a pulp -by the rush of water. Special 

 cruising for the purpose seems to be the only thing 

 that can answer. 



How much scientific wealth has been gained by a 

 few hours' deep-sea dredging by Dr. Carpenter in 

 his recent trip in H.M.S. Lightning ! Perhaps we 

 may venture to hope that those who wield the 

 mighty naval resources of our nation, may one day 

 see fit to afford facilities for searching the surface 

 as well as the bottom of the realm they rule on 

 behalf of Britannia. 



Bury Cross, Gosport. 



A SUCTOKIAL ANIMALCULE. 



OE the many curious organisms belonging to the 

 class Infusoria, none are more curious aud 

 interesting than the various forms of Acinette. They 

 may in general terms be described as amoeba-like 

 masses of sarcode enclosed in a structureless, trans- 

 parent integument, pyriform, ovoid, or spherical in 

 shape, and furnished with rigid and elastic filaments 

 or tentacles, which are retractile, and either acute 

 or knobbed at the extremity; the body being at- 

 tached by a stalk of variable length to some vege- 

 table or animal substance. 



Acineta tuberosa is a commonly occurring form in 

 brackish water. To this species chiefly I shall con- 

 fine my remarks. 



The specimens which came under my observation 

 recently were in the broadest part only 5-00 of an 

 inch, and when magnified 350 diameters presented 

 the appearance figured below. 



The organism is destitute of any mouth or similar 

 orifice, shows no ciliary action at any part, but 

 possesses a pulsating vesicle. The body is filled 

 more or less with bright colourless granules, and 

 assumes various shapes within the transparent in- 

 tegument. 



The filaments radiating from the angles are 

 capable of entire contraction, and in this state are 

 quite invisible within the substance of the body ; so 

 that they are apparently mere expansions of sarcode, 

 and not distinct organs. They extend frequently 

 to double or treble the diameter of the body, and 

 each filament at its extremity is of a convexo-conical 

 form. They are perfectly rigid, but elastic, ten or 

 eleven in number at each angle of the body, and are 

 spread out in all directions, no two being of the same 

 length. 



Attached by its thin daik stalk to a filament of 

 conferva or other substance, Acineta remains quietly 

 and patiently awaiting prey, like a spider in its web, 

 or like an actinia with its tentacles expanded. 

 There is a slight movement occasionally, of the fila- 

 ments, but for the most part they remain quite 

 motionless. Any small animalcule wandering in 

 their neighbourhood is sporting on dangerous 



ground, for so sure as it comes into contact with 

 the extremity of one of those delicate, almost in- 

 visible filaments, so sure does adhesion take place, 

 aud it struggles in vain to escape. If strong and 

 lively, it will pull Acineta on one side and bend the 

 attaching filament in all directions; but Acineta will 

 bring an additional tentacle or two to bear upon its 

 obstreperous victim, and thus render escape impos- 

 sible. During all this time Acineta exhibits no 

 excitement, but quietly retains its grasp, and if it 

 has been pulled awry by the captive, gradually re- 

 adjusts itself to its original position. The ciliary 

 action of the prey then grows gradually languid, 

 and sooner or later, according to its degree of vigour 



Fig. 77. Acineta tuberosa. 



and vitality, entirely ceases. No attempt is made 

 by the Acineta to draw the prey towards its body. 

 He simply commences quietly to suck its life-juices 

 by means of the hollow filaments which have effected 

 attachment. This is of course a rather slow process 

 with sucking tubes of such extreme tenuity, but it 

 goes on surely if slowly. 



If observed after the lapse of some hours, it will 

 be seen that Acineta has grown plumper, and that 

 its prey has not only diminished in size but become 

 a mere empty sac. When quite done with, attach- 

 ment is broken, and the rejected carcase is suffered 

 to float away. This process of imbibing the juices 

 of its prey occupies sometimes three or four days 

 when the latter is unusually large. On one occasion 

 I witnessed a Paramecium at least twice the bulk 

 of the Acineta caught in its grasp. In two days the 



