Archive image from page 161 of Discovery reports (1932) Discovery reports discoveryreports06inst Year: 1932 148 DISCOVERY REPORTS series of embryo Eudyptes by Max Lewin (1903) and they apply equally well to the Ring penguin. The cartilaginous skeleton at this stage is rapidly under- going replacement by bone. Ossification of the chief ele- ments of the axial skeleton is proceeding and to some extent also replacement of the basic cartilages of the skull. The brain, with the completion of the cerebellum, takes on the aspect and proportions of that of a typical bird. The eye, as shown in Plate
Archive image from page 161 of Discovery reports (1932) Discovery reports discoveryreports06inst Year: 1932 148 DISCOVERY REPORTS series of embryo Eudyptes by Max Lewin (1903) and they apply equally well to the Ring penguin. The cartilaginous skeleton at this stage is rapidly under- going replacement by bone. Ossification of the chief ele- ments of the axial skeleton is proceeding and to some extent also replacement of the basic cartilages of the skull. The brain, with the completion of the cerebellum, takes on the aspect and proportions of that of a typical bird. The eye, as shown in Plate VI, fig. 2, develops a large pecten {pe) on its floor and the eyelids close. The pecten in most birds is single, and it first arises in the penguin as a simple lamellate process. By the time the embryo is ready to hatch, however, this sheet of tissue is divided into ten units (the teeth of the comb) which adhere to one another only by their tips (Fig. 3 a). With regard to the viscera, the stomach lies on the left side of the body and the much-coiled intestine is thrust dorsally Fig. 2. Left hind-limb, Gentoo and to the right side of the coelomic cavity by the yolk sac. penguin embryo, stage 37 . . . (Plate IV) The rectum opens into the cloaca, which receives the meta- nephric ducts (Plate VI, fig. 2, x), genital ducts (Plate VI, fig. 2,3'), and the bursa Fabricii. At the earlier stage (Plate V, fig. i) the bursa {bf) is a sac of large dimensions. It has dwindled in proportion very considerably by the time hatching is imminent. Rudiments of both gonads, with their ducts, are present in these later stages of the development, although in penguins, as in other birds, the right ovar}' and right Miil- lerian duct are atrophied in the adult. The large proportions of the gall bladder in relation to the liver is illustrated in Plate VI, fig. I, gh. It is rather puzzling to explain the excessive secretion of bile that this indi- It may be associated with the habit of
Size: 1051px × 1903px
Photo credit: © Bookend / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
