. Chimæroid fishes and their development. Fishes; Chimaeridae. 42 CfllM^ROin FISHES AND THEIR DEVELOPMENT. THE EGG AND ITS MEMBRANES. In the newly deposited capsule the egg measures 35 by 20 by 12 mm., but it is smaller, together with the capsule, if taken from young fish (cf. the size of the capsules shown in plate 11, fig. 10, and plate in, fig. 17), as is also the case in sela- chians (Riickert). Its consistency becomes less fluid-like as development advances; thus, shortly before breaking from the ovarian membrane, the egg has so little con- sistency that it will flatten out to the diamete
. Chimæroid fishes and their development. Fishes; Chimaeridae. 42 CfllM^ROin FISHES AND THEIR DEVELOPMENT. THE EGG AND ITS MEMBRANES. In the newly deposited capsule the egg measures 35 by 20 by 12 mm., but it is smaller, together with the capsule, if taken from young fish (cf. the size of the capsules shown in plate 11, fig. 10, and plate in, fig. 17), as is also the case in sela- chians (Riickert). Its consistency becomes less fluid-like as development advances; thus, shortly before breaking from the ovarian membrane, the egg has so little con- sistency that it will flatten out to the diameter of about 45 mm. (jilate 11, fig. 5). Its ellipsoidal outline is assumed when inclosed in the capsule. It will, however,. Fig. 30.—Early ovarian egg ol Chimaera colliei. Seclion through major axis of egg. gs, Gonadial sinus; i,-?', germinative vesicle — around it the extent of the space indicates the size of vesicle before fixation; o, stalk attaching egg to ovary and inclosing the arterial blood supply; /, peritoneum ; /, tunic (^ granulosa). Figs. 31 and 32. —Sections of the marginal region of ovarian eggs (the first measuring about 5 mm. in diameter, the second about 15 mm.), indicating changes in the tunic and the development of yollc. bm. Basement membrane (between the tunic and the egg); by, botryoidal yolk masses developed in vacuoles in germinal yolk; i, layers of connective and vascular tissue theca in ovarian membrane surrounding egg; .^'.s', gonadial sinus; f, peritoneum; /.tunic of ovarian tissue inclosing egg (follicular epithelium); /, inmost layer; m, middle layer; o, outmost layer; zr, zona radiata. X 585. present an almost spherical form (horizontal outline 25 by 20 mm.) if the constricting capsule be opened (plate 11, fig. 8). In later stages it has the consistency of thick cream. THE OVARIAN MEMBRANES. Comparison with corresponding stages in shark (Pristiurus) shows that the wrappings of the ovarian eggs of Chimaera are the more complex. In earl}' sta
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectfishes, bookyear1906
