CffiLELMINTHA. 99 



CHAPTER VII. 

 NEMATONEURA. 



CffiLELMINTHA* (Owen). 



Vers Intestinaux cavitaires (Cuv.) ; Nematoidea (Rudolplii). 



The entozoa which belong to the nematoneurose division 

 of the animal kingdom have long been separated in zoological clas- 

 sification from those which have been described in the last chapter, 

 on account of the superiority of their internal organization. In 

 the STERELMINTHA, or parenchymatous forms, we have seen the 

 digestive process carried on in canals simply excavated in the sub- 

 stance of the body, without any anal outlet for the discharge of 

 superfluous matter; the nervous system either perfectly diffused 

 through the tissues, or but obscurely visible even in the most per- 

 fect species, and the muscular tissue, as a necessary consequence, 

 scarcely aggregated into distinct fibres : the sexes, moreover, except 

 in the Echinorynchi, which form the transition from the more im- 

 perfect to the more elevated type of structure, have been invariably 

 combined in the same individual. But we now arrive at a point 

 in the scale of animal developement at which the nervous fibre be- 

 comes for the first time distinctly recognisable, forming a more 

 perfect means of intercourse, if we may be allowed the expression, 

 between the different parts of the body ; the muscular contractions, 

 being thus more intimately associated, assume far greater energy, 

 and muscular fasciculi are distinguishable, arranged in precise and 

 definite directions ; the alimentary canal is visible as a separate 

 and distinct tube, enclosed with other viscera in an abdominal 

 cavity; and the ovigerous and impregnating sexual organs are 

 found to exist in different individuals. Still, however, we find 

 no nervous centres developed, or the ganglia which exist are so 

 extremely minute and rudimentary that in no case can we suspect 

 the existence of organs appropriated to the higher senses ; the 

 sensations of all the tribes composing this division of the animal 

 world are therefore apparently limited to the generally diffused 



* xo7*.o, hollow 'fafuvs-ivfaf, a worm. 



H 



