OCEAN LIFE. 29 



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ted into the general cavity of the body through a set of minute 

 membranous tubes seen upon the exterior of the animal, bathes 

 all the viscera, and consequently ensures a complete exposure of 

 the circulating fluids to the influence of oxygen, the whole 

 peritoneal surface performing the office of a respiratory apparatus. 

 " The nervous apparatus of the Asteridse, consists of a simple 

 circular cord, which runs around the mouth of the animal; from 

 this ring, three delicate filaments are given off opposite to each 

 ray, one of which according to Tiedemann, runs along the centre 

 of the ambulaceal grove upon the under surface of the body, 

 and gives minute twigs to the locomotive suckers placed on each 

 side of its course ; the other two filaments, pass into the visceral 

 cavity, and are probably distributed to the internal organs. 

 There are no ganglia developed on any part of this nervous ap- 

 paratus ; or at least, if, as some writers assert, ganglionic en- 

 largements are visible at the points whence the radiating nerves 

 are given off, they are so extremely minute as not in any degree 

 to merit the appellation of nervous centres." " The general 

 sense of touch in the Asteridse is extremely delicate, serving not 

 only to enable them to seize and secure prey, but even to recog- 

 nise its presence at some little distance, and thus direct these 

 animals to their food. Any person who has been in the habit of 

 fishing with a line in the shallow bays frequented by star-fishes, 

 and observed how frequently a bait is taken and devoured by 

 them, will be disposed to admit this ; yet to what are we to at- 

 tribute this power of perceiving external objects ? It would 

 seem most probably due to some modification of the general 

 sensibility of the body, allowing of the perception of impressions 

 in some degree allied to the sense of smell in higher animals, 

 and related in the character to the kind of sensation by which 

 we have already seen the Actiniae and other polyps able to ap- 

 preciate the presence of light, although absolutely deprived of 

 visual organs." 



