236 Miscellaneous. 



appearances, due probably to compression, and that they have not 

 seen the true arrnnijement of the peripheral ncrvoug system of these 

 little creatures. As this arrangement is really very remarkable, I 

 shall now give a short description of it. 



Beneath the cuticle, which is smooth or striated, but alVaya 

 structureless, we tind a very thin and very refractive granular 

 layer. This layer has neither been figured nor described by M. 

 Marion; but Dr. Charlton Bastian*, in 1806, indicated it very 

 clearly, and even recognized that it contained cells. To investigate 

 it properly it is necessary to macerate entire worms in a mixture 

 of acetic acid, alcohol, glycerine, and water — a mixture which has 

 already rendered me great service in many cases, and the formula 

 of which I have given in my ' Monographic dcs Dnigonneaux.' 

 The marine Xematoids, when immersed in this liquid, quickly be- 

 came perfectly transparent. We can then see very distinctly that 

 the granular layer situated between the skin and the muscles con- 

 sists in great part of very fine fatty granules, and that it contains, 

 scattered through it, small stellate cells furnished with a very re- 

 fractive nucleus. 



The relations of these little cellular bodies to the setoe or papillae 

 are easily ascertained. In a longitudinal section we perceive very 

 distinctly that from the apex of each cell, perpendicularly to the axis 

 of the animal, issues a very delicate thread which, after having tra- 

 versed the whole thickness of the cuticle, arrives at the base of the 

 papilla and enters it ; but each cell also furnishes laterally a certain 

 number of processes which place it in relation with the neighbouring 

 cells ; and it is equally easy to ascertain this, if, instead of making a 

 section of the animal, we endeavour to follow the granular layer 

 over a certain portion of its surface, by gradually raising the object- 

 glass of the microscope. The subcutaneous layer of the marine 

 Nematoids, therefore, contains a true network of ganglionic cells, 

 which furnish nervous threads both to the organs of touch and to 

 the organs of vision. This peripheral network is in relation with the 

 central nervous system by means of a plexus, which traverses the 

 muscular layer and unites the ventral nerve with the subcutaneous 

 layer. 



These are undoubtedly facts of detail and of delicate observation ; 

 but still they are of importance, for they are not isolated. It will 

 suffice for me to recall that various observers have indicated a very 

 analogous network in the Actinia, and that I have myself described 

 one exactly similar in Gordius. This network arrangement of the 

 ganglionic cells is certainly less rare in the Invertebrata than has 

 hitherto been supposed; and it is probable that it represents in 

 itself the whole of the nervous system of inferior types. — Compies 

 Bendus, February 8, 1875, p. 400. 



* " On the Anatomy and Physiology of the Nematoids, parasitic and 

 free," Phil. Trans. 1800, vol. clvi. part 2, pi. xxnii. fig. HG, d. 



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