HYDRA. 1(J3 



composing the principal bulk of the body.* These 

 grains, when pressed out of the flesh into water, are 

 scattered indiscriminately ; and appear to have 

 been united in the living animal, by means of this 

 glutinous material. 



No perceptible fibres, either muscular, or of any 

 other kind, can be detected in the flesh of the poly- 

 pus : nor is there the least indication of the forma- 

 tion of transverse rings, similar to those which 

 exist in worms, and which, in these latter animals, 

 contribute to progressive motion. Every portion 

 of the substance of the body is equally irritable and 

 contractile, and its movements appear to be go- 

 verned by some voluntary power belonging to the 

 animal, and directed to the attainment of certain 

 ends. The softness and pliancy which it possesses 

 allow of its being closely fitted to all the inequali- 

 ties of the surface of the bodies to which it is ap- 

 plied ; and perhaps this cause alone occasions it to 

 adhere with great force to these bodies, without the 

 aid of any glutinous fluid. A conjecture, which 

 has much appearance of probability, has been 

 offered, that this power of adhesion is derived from 

 the presence of a great number of exceedingly mi- 

 nute disks, interspersed over every part of the sur- 

 face, constituting so many suckers, and resembling, 

 though on a very diminutive scale, the sucking ap- 

 paratus on the arms of the cuttle-fish. 



The minute structure of this tribe of polypi has 

 been much elucidated by the recent discoveries of 



* To this peculiar gelatinous substance, which composes the chief 

 part of the substance of polypi, and of the lower order of infusory 

 animalcules, Dujardin has given the name of Sarcode. Ann, Sc. 

 Nat. serie 2, iv. 367. 



