. The microscope and its revelations. ijciji-u>iju» ui . -. Terebella concMlega : a, labial ring; Species to occupy the space that b, b, tentacles; c, first segment of intervenes between the outer sur- the trunk; <7 skin of the back; e face of the alimentary caiial and pharynx; f,intestine; ,, n /? ,1 i •, muscles of the inferior surface of the the iner wall of the body, and to body; h, glandular organ; i, organs pass from this into canals which of generation ;j, feet; M, branchiae; often ramify extensively ill the/. dorsal vessel acting as a respiratory . J heart; m, dor
. The microscope and its revelations. ijciji-u>iju» ui . -. Terebella concMlega : a, labial ring; Species to occupy the space that b, b, tentacles; c, first segment of intervenes between the outer sur- the trunk; <7 skin of the back; e face of the alimentary caiial and pharynx; f,intestine; ,, n /? ,1 i •, muscles of the inferior surface of the the iner wall of the body, and to body; h, glandular organ; i, organs pass from this into canals which of generation ;j, feet; M, branchiae; often ramify extensively ill the/. dorsal vessel acting as a respiratory . J heart; m, dorso-intestinal vessel; respiratory organs, but are never, venous sinus surrounding oesopha- furnished with a returning series of passages; and second, a fluidwhich is usually red, contains fewfloating particles, and is inclosed ina system of proper vessels that communicates with a central pro-pelling organ, and not only carries the fluid away from this, but alsobrings it back again. In Terebella we find a distinct provision for the. FIG. 715.—Circulating apparatus of gus; ;;, inferior intestinal vessel;o, o, ventral trunk ; p, lateral vascularbranches. 1 For an interesting account of the formation of these tubes see Mr. A. T. Watsonspaper in Jaitrn. Iloij. Micr. Snc. 1890, p. 685. DEVELOPMENT OF WORMS 949 aeration of both fluids ; for the first is transmitted to the tendril-like tentacles which surround the mouth (fig. 715, b, b), whilst thesecond circulates through the beautiful arborescent gill-tufts (k, Jc}situated just behind the head. The former are covered with cilia, theaction of which continually renews the stratum of water in contactwith them, whilst the latter are destitute of these organs; and thisseems to be the general fact as to the several appendages to whichthese two fluids are respectively sent for aeration, the nature of theirdistribution varying greatly in the different members of the class. Inthe observation of the beautiful spectacle presented by the re
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
