Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . tunic is sometimesrough and warty, the inner surface alwayssmooth and lubricous. Microscopicallyexamined, it consists chiefly of a conglo-merate of non-nucleated cells like the pa-renchyma of Cacti; chemically analysed,100 parts of the tissue, free from ash andwater, gives of carbon 45*38, Hydrogen6*47; being the same composition as the cellulose of This non-azotisedtissue is traversed by large blood-vessels,and towards its inner surface crystals andnuclei are
Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . tunic is sometimesrough and warty, the inner surface alwayssmooth and lubricous. Microscopicallyexamined, it consists chiefly of a conglo-merate of non-nucleated cells like the pa-renchyma of Cacti; chemically analysed,100 parts of the tissue, free from ash andwater, gives of carbon 45*38, Hydrogen6*47; being the same composition as the cellulose of This non-azotisedtissue is traversed by large blood-vessels,and towards its inner surface crystals andnuclei are abundant in the clear homo-geneous basis. The lining membrane iscomposed of a layer of polygonal, nucle-ated, epithelial cells. The second tunic is muscular; it ad-heres to the outer tunic at the circumfe-rence of the two orifices, and is connectedto it by blood-vessels at a few other points ; elsewhere it is quite free,and the opposed surfaces of the intervening space between the mus-cular and elastic tunics has the aspect of a serous cavity. Its finefasciculi of fibres are remarkably distinct, and are arranged in two. Ascidia mammillata. * Preps. Nos. 614, 615, 616. 785, 898 b. 998. 1303 IX. p. 34. 4 474 LECTURE XX. layers,—the external circular, the internal longitudinal. The fibresor fasciculi of the outer layer are smaller than those of the inner one,and less regularly disposed. They describe regular circles around theprocesses leading to the orifices of the shell. Other fibres of the outerlayer pass transversely from one tube to the other. The longitudinalfasciculi radiate from the two orifices, and decussate each other,winding round the bottom of the sac. Deeper, again, than this layerthere is a sphincter surrounding the base of each tube, or orifice, fromwhich a third more delicate layer of longitudinal fibres is given off. Of the two more or less protuberant and stellate apertures in theouter tunic, one (b) leads directly into the muscular sac, the other (a)into
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1850
