THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTOEY. 



[FIFTH SERIES.] 



No. 119. NOVEMBER 1887. 



XLII. — The True Nature of the" Madreporic System " of Echi- 

 nodermata, with Remarks on Nephridia. By Prof. Marcus 

 M. HAEToa, D.Sc, M.A., F.R.U.I.* 



Sharpey, in his article on " Echinodermata " in Todd and 

 Bowman's ' Cyclopsedia of Anatomy and Physiology,' writes : 

 " If the liquid contained in the feet of the starfish be sea- 

 water, either pure or with an admixture of organic particles, 

 which is probable from its chemical composition, may it not 

 be introduced and perhaps again discharged through the 

 pores of the disk [sc. madreporite] and the calcareous tube, 

 the porous disk serving as a sort of filter to exclude im- 

 purities ? " He also describes the perivisceral liquid as a 

 " clear fiuid which, when filtered, yields no trace of animal 

 matter, but agrees almost entirely in composition with sea- 

 water." 



These observations^ apparently unchecked by subsequent 

 experiment, seem to have been the origin of the widely 

 adopted views that the cavities of Echinodermata are filled 

 with sea-water directly taken up pro re natd through the 

 madreporite and madreporic canal, which for brevity we may 



* This paper was read in a less complete form at the British Associa- 

 tion, Manchester, 1887. 



Ann. & Mag. N, Eist. Ser. 5. Vol. xx. 23 



