1867.] Nerve Structure and Force. 157 



but of this we have no anatomical nor optical proof; moreover, of 

 what use would sight be to an animal so incapable of pursuit and 

 unfit to avoid danger ? They can serve no sexual purpose, for male 

 and female organs are combined in the same animal. They may 

 by their brightness attract other occupants of the ocean which are 

 suitable for food, or they may be some of the earliest traces of 

 nerve structure, acted on by light, and serving to direct the move- 

 ments towards those regions where life may be best maintained. 



Siebold expresses the opinion of most observers in saying that 

 as yet only a very rudimentary and imperfectly-distinguished 

 nervous system has been made out in the polyp ; this consists of 

 round masses, which are regarded as composed of nervous matter 

 (ganglia) situated iu the parenchyma. A ganglion of this kind 

 has been supposed to have been observed about the mouth. Inves- 

 tigations upon their organs of sense have not been more successful. 

 However, the sense of touch appears developed over the whole 

 surface of the body, but especially so in the extremely irritable arms 

 and tentacles; but, as yet, no tactile nerves have been found in 

 these parts. In the same manner, light, to which these animals 

 show a greater or less sensibility, is perceived rather by the general 

 surface of the body than by special organs. There are, however, in 

 some species, at particular stages of development during which 

 they swim freely about, certain nicely-defined structures situated 

 upon the sides of the body, and which may be regarded as special 

 organs of light and sound. This is the case with Syncoryne; 

 and Coryne has in then place four red organs, which correspond 

 exactly to those found on the border of the disc of the pulmograde 

 Acalejphse, and which have been regarded as organs of sense. The 

 organ seen at the base of the six arms of Eleutheria dichotoma has 

 quite the appearance of an eye ; that is, there can be distinguished 

 in it a cornea, a crystalline lens, and a red pigment layer surround- 

 ing the whole. 



The Rev. "W. Bingley, the author of an old but well-known 

 work on Animal Biography, gives the following quaint but truthful 

 account of the earth-worm, or as he calls it, the dew-worm (Luin- 

 hrieus terrestris) : — " The most insignificant insects and reptiles are 

 of much more consequence, and have much more influence in the 

 economy of nature, than the incurious are aware of; and are 

 mighty in their effect from their minuteness (which renders them 

 less an object of attention) and from their numbers and fecundity. 

 Dew-worms, though in appearance a small and despicable link in 

 the chain of nature, yet if lost, might make a lamentable chasm ; 

 for, to say nothing of half the birds and some quadrupeds which 

 are almost entirely supported by them, worms seem to be the great 

 promoters of vegetation (which would proceed but ill without them) 

 by boring, perforating, and loosening the soil, and rendering it 



