442 



EOTIFEKA. 



Fig. 229. 



Lower half of the body of Melicerta 

 ringens, highly magnified : a, lower 

 stomach ; 6, c, lower portion of ovary 

 and oviduct ; d, intestine; e, filamentary 

 spermatic tube (?) ; /, g g, retractor 

 muscles; A, corpuscles swimming in 

 the peri-intestinal fluid, regarded by 

 Ehrenberg as nervous ganglia. 



objects arc delineated as they appeared in one individual, in the clear 



space immediately below the viscera. They differ as widely as possible 



in their size, number, and proportion. So far from being nervous vesicles, 



they appear rather to be cells modified into a rudimentary form of 



areolar tissue. That they are hollow 



vesicles or cells, very viscous, readily 



cohering, and, owing to this coherence, 



easily drawn out by the movements of 



the various organs to which they are 



attached, are facts capable of easy 



demonstration. 



(1144.) Leydig conceives the nervous 

 system of Lacinularia to consist of, 

 first, a ganglion situated behind the 

 pharynx, composed of four bipolar cells 

 with their processes; secondly, of a 

 ganglion at the beginning of the caudal 

 prolongation, composed of four larger 

 ganglionic cells and their processes. 

 The last-mentioned cells are described 

 by Professor Huxley as vacuolar thick- 

 enings finding no difference whatever 

 between them and the thickenings in 

 the disk, which Leydig himself allows to be mere thickenings. 



(1145.) Professor Huxley's own view upon the subject is as follows* : 

 On the oral side of the neck of the animal, or, rather, upon the under 

 surface of the trochal disk, just where it joins the neck, and therefore 

 behind and below the mouth, there is a small hemispherical cavity, which 

 seems to have a thickened wall and is richly ciliated within. Below 

 this sac, but in contact with its upper edge, is a bilobed homogeneous 

 mass, which Professor Huxley believes to be the true nervous centre. 



(1146.) On the nuchal region of many species of Kotifers are two 

 remarkable organs (fig. 227, 1, d cZ), which, from their structure, appear 

 to perform the office of tentacula, although various uses have been 

 assigned to them by different observers. Ehrenberg supposed them to 

 be connected with the respiratory functions, while Dujardin compares 

 them, with much greater probability, to the antennae and palpi of the 

 Entomostracous Crustaceans. In Melicerta ringens^, these organs, when 

 fully protruded, are seen to be terminated by a brush of fine divergent 

 setae (fig. 227, 2, a), implanted on the convex side of a small deltoid 

 body (6) ; from the flat side of this latter appendage there proceeds 

 along the interior of the tube, towards the body of the animal, a delicate 

 muscular band (c), which by its contractions draws the deltoid body 

 backwards, thus inverting the extremity of the tube, and forming a 

 * Quarterly Journal of Microscopical Science, no. 1. p. 9. t Williamson, foe. cit. 



