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1 86 NATURE AND AFFINITIES OF THE SPONGES.enumerated, it has yet to be recorded that it very commonly happens thatthese structures present an altogether irregular and asymmetrical contour.Illustrations of such irregular formations, as figured by Oscar Schmidt, ofGrantia (Sycandrd) compressa, and as observed by the author, willbe foundreproduced at PI. IX. Figs. 32 and 35. Such asymmetrically developedgemmules may retain fundamentally the moruloid or amphiblastuloidstructural type, being in the one case composed entirely of similar and inthe other case of dissimilar constituents. The fact that these variousirregularly formed gemmules are by no means of rare occurrence, maybe accepted as furnishing supplementary evidence in demonstration of thenon-correspondence of these sponge-gemmules, or so-called ciliated larvae,with the embryos of the typical Metazoa, and in which latter organicseries the production of asymmetrical germs is quite exceptional. One ofthe strongest arguments furnished in support of the essentially Protozoicsignificance of these reproductive bodies is, undoubtedly, afforded by theindependently contributed testimony of Oscar Schmidt and Metschnikoff,by both of whom it is shown that in the case of Ascetta primordialis,the component flagellate elements of the moruloid gemmule assumequite independently an amoeboid condition, and retiring separately intothe central segmentation cavity, undergo their further metamorphoses.Ultimately, these separately retreating amoebiform units completely fillup the central cavity, and burst through the posterior region of theciliated body, project at this extremity, and so produce in a roundaboutmanner a pseudo-amphiblastula. It will be at once recognized thatwhile this peculiar developmental phenomenon of the sponge-gemmuleexhibited by Ascetta primordialis, is altogether opposed to anything thatobtains among the Metazoic series, it is at once reconcilable with aProtozoic interpretation. With their near allies the simple flagellate orcollared monads, e.g. Phalansterhim,Spongomonas, and Protospongia, parallelphenomena, including the assumption by the adult zooids of an amoeboidstate, and their retreat within the common gelatinous cytoblastema-likematrix, or zoocytium, represents the normal reproductive process.The highly important evidence that demonstrates the thoroughgoingProtozoic affinities of the sponge with relation to the primary origin anddevelopment within the parent sponge-stock of the free-swimming ciliatedgemmules, has yet to be submitted. The initial condition of these reproductivestructures, as conceded unanimously by the independent testimonyof every investigator, takes the form of an amcebiform body, varying in sizefrom the i-3OOOth to the i-2OOth of an English inch, and presents a considerablelikeness to the primary condition of an ordinary ovum. With,however, the interpretation of the significance and subsequent evolution ofthis amcebiform structure that is most generally advocated, the author hasto declare himself entirely at issue. In accordance with this more widelyaccepted view, the amcebiform body is a true ovum, developed separatelyand independently in the interstitial substance of the sponge, and after-