The porifera and coelentera . posterior pole, and a central mass of granularamoebocytes (Fig. 59, 3, and Fig. 60, e). During the free swimmingperiod the ciliated gastral la^er becomes partially overgrown by the The accnunt liere piveii dilliTs from that of Schiilze, who ivj^anUil these granularcells as the future ckniial layer ; for this reason Sclmlze distingiiislietl the posteriornon-ciliated cells of the aniphiMastula as granular cells {Kur-ncrzcUeii), from theflagellateil cells, though as a matter of fact the latter are in reality the more granularof tlie two, since they contain yolk, whic
The porifera and coelentera . posterior pole, and a central mass of granularamoebocytes (Fig. 59, 3, and Fig. 60, e). During the free swimmingperiod the ciliated gastral la^er becomes partially overgrown by the The accnunt liere piveii dilliTs from that of Schiilze, who ivj^anUil these granularcells as the future ckniial layer ; for this reason Sclmlze distingiiislietl the posteriornon-ciliated cells of the aniphiMastula as granular cells {Kur-ncrzcUeii), from theflagellateil cells, though as a matter of fact the latter are in reality the more granularof tlie two, since they contain yolk, which in the dermal cells becomes worked upand absorbed more quickly. The statements here made are based upon my own ob-servations upon leucosolenia, and the figures of Barrels for Sycon ami Grantia; seealso Dendy (1889). SPONGES 77 iion-ciliated dermal layer (Fig. 60,/), the cells of which may formprecocious spicules, so that both the metamorphosis and the histo-genesis may be said to begin before fixation and during the larval. Fig. 00. Developiiient of Si/coti raphamis (after Schulze). o, dviini; b, c, ovum segmentiiii,—?) as sepiifrom above, c, as seen from the side ; il, blastosphere with eifrhtC/) posterior gnmular cells(archaeocytes),(listiiii;iiisli(>(l by their darker ajipeaiance; c, free swimmiiif; larva (aniphiblastula);the more centrally placed archaeocytes are not seen ; /, later stage of the same, showing theciliated cells becuming overgrown by the non-ciliateil ; a, optical section of pupa in which thegastral cavity has appeared ; note the two rounded cells, evidently porocytes, bordering on thecavity; h, j, young si)onge (0/v/i».<) showing the newiy-fornied osculum with an iris-likecontractile membrane from which the oscular rim is formed ; h in side view, j, seen from above. period. If we compare this larva witli that of Lencosohnia, as de-scribed above, we see that it differs from it only in the fact thatthe germ layer formation is thrown back, so to spea
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