Text-book of comparative anatomy . the chief axis, just like the cross axes of the Medusa, eachaxis consisting of two opposite perradii. While, however, in theradially constructed Medusa the cross axes are quite similar, and theplanes which run through them in the chief axis divide the body intofour entirely similar quarters, the two cross axes in the Ctenophora arenot alike, and the lateral and median planes divide the body into fourquarters, of which only the two which are diametrically opposite aresimilar. Either of the two planes by itself, however, cuts the bodyinto two similar halves. At
Text-book of comparative anatomy . the chief axis, just like the cross axes of the Medusa, eachaxis consisting of two opposite perradii. While, however, in theradially constructed Medusa the cross axes are quite similar, and theplanes which run through them in the chief axis divide the body intofour entirely similar quarters, the two cross axes in the Ctenophora arenot alike, and the lateral and median planes divide the body into fourquarters, of which only the two which are diametrically opposite aresimilar. Either of the two planes by itself, however, cuts the bodyinto two similar halves. At the aboral pole of the Ctenophora, as opposed to all other Ccdcn- II CNIDARIA—GENERAL 79 ttrata, there is a complicated sensory organ, the sensory body, which,according to its structure, is best described as an auditory organ, butperhaps serves for regulating the position of the body in the water. From near the aboral to near the oral pole, there run along thesurface of the body in 8 meridians 8 rows of swimming plates, the so-. Fit;. OS.—Hormiphora plumosa, after Chun. A aud B, From the side: A, seen in the directionc-d in Fig. C; B, seen in the direction o/ in Fig. C. C, As viewed from the aboral or sensorypole, a-b, Chief axis ; c-d, direction of the median plane ; c-/, direction of the lateral plane ; a,oral; 6, aboral pole ; m, stomach; s, oesophagus ; 53, cesophageal vessels; tg, tentacular vessels ;ag, aboral vessel; r, ribs; te, tentacle sheath; pp, polar plates. D, Portion of a transversesection through the oesophagus (s); ft, tentacle base ; sw, cesophageal papillae ; ga, branches ofthe tentacular vessel. called ribs (/•). If we use the terms applied to the Medusa, these ribsare adradial. Between oesophagus and stomach on the one side and the outerintegument on the other, there is a jelly which is strongly developedin most Ctenophora, and in which various tissue elements are imbedded. Gastro-canals, lined with endoderm, similar to the radial canals of 80 COMPAR
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
