The porifera and coelentera . Peripatus. At the same time Ishowed from injections and silver impregnations of Anodon,Cephalopods, Astacus, and Limulus, that true capillaries are incertain regions of the l)ody in both Mollusca and Arthropodamore largely developed than is generally supposed. I showedthat the far-spreading tubules of the organ of Keber in Molluscs,and probably also a system of spaces in the connective tissues of PHLEBCEDESIS IN CHALTOPODA 27 Astacus and of Limulus, should be regarded as remnants of thecoelom, the bulk of which has been filled up by swollen blood-vessels, leaving
The porifera and coelentera . Peripatus. At the same time Ishowed from injections and silver impregnations of Anodon,Cephalopods, Astacus, and Limulus, that true capillaries are incertain regions of the l)ody in both Mollusca and Arthropodamore largely developed than is generally supposed. I showedthat the far-spreading tubules of the organ of Keber in Molluscs,and probably also a system of spaces in the connective tissues of PHLEBCEDESIS IN CHALTOPODA 27 Astacus and of Limulus, should be regarded as remnants of thecoelom, the bulk of which has been filled up by swollen blood-vessels, leaving only epinephric and gonadial sacs in the Arthro-poda, pericardial and gonadial sacs in the INIollusca. Some years later my assistant, Dr. Benham, now Professor inDunedin, New Zealand, described (Quart. Jour. Micr. Sci. ) a condition of the blood-vessels in the Chajtopod Magelona,which is parallel to that through which the vessels of ancestralMolluscs and Arthropods must have passed. Phlebredesis is carried Dv. LexC. ?obL lattxt dor. y. JTV. ctrc Fio. 14.—Traxsverse Section of the Thoracic Region of the MaoelonaTO show the swelliso of the Blood-vessels and consequent reduction of the CtELOM. , dorsal vessel; G, gut; .V, nerve conl; , ventral vessel greatly swollen,filled with a peculiar corpusculated blood ; , lateral extension of the same; cr>\coelom; , lateral vessel; , longitudinal muscles; circ, circular muscles; obi,oblique muscles ; , dorso-ventral muscle. (After Benham.) to such a point in Magelona as to extinguish to a large extentthe proper ccelomic cavity (see Fig. 14). This observation seemsto be of importance as showing the tendency to Phleboedesis inChsetopods among the ancestors of which the ancestors of bothMollusca and Arthropoda are in all probability to be we remember further that in some Cha^topods the cellswhich should form the blood-vessels and the blood, may actuallybreak up altogether and give
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