. The elements of embryology. Chickens -- Embryos. •() THE SECOND DAY. [CHAP. situate in the envelopes of the nodal groups, as well as those lying on the exterior of the connecting processes, appropriate a quantity of the granular protoplasm surrounding each, and thus become converted into spindle-shaped cells. Each nodal group and each connecting process thus gets a distinct wall of nucleated cells. By the continued widening of the connecting processes and solution of their central portions, accompanied by a corresponding increase in the enveloping nucleated cells, the original protoplasmic n
. The elements of embryology. Chickens -- Embryos. •() THE SECOND DAY. [CHAP. situate in the envelopes of the nodal groups, as well as those lying on the exterior of the connecting processes, appropriate a quantity of the granular protoplasm surrounding each, and thus become converted into spindle-shaped cells. Each nodal group and each connecting process thus gets a distinct wall of nucleated cells. By the continued widening of the connecting processes and solution of their central portions, accompanied by a corresponding increase in the enveloping nucleated cells, the original protoplasmic network is converted into a system of communicating tubes, the canals of which contain blood-corpuscles and plasma, and the walls of which are formed of spindle-shaped nucleated cells. Fig. Surface View from below of a small portion of the posterior end of the pellucid area OF A 36 HOURS' Chick. To illustrate the formation of the blood-capillaries and blood-corpuscles, magnified 400 diameters. 6. c. Blood-corpuscles at a nodal point, already beginning to acquire a red colour. They are enclosed in masses of protoplasm in the outermost layer of which are found nuclei, a, some of which contain two nucleoli. These nuclei subsequently become the nuclei of the cells forming the walls of the vessels. The nodal groups are united by protoplasmic processes (), also containing nuclei with large nucleoli («). These nuclei increase in number by division, and become converted in part into the nuclei of the cells forming the walls of the vessels, and in part into blood-corpuscles. The blood-corpuscles pass freely from the nodal points into the hollow pro- cesses, and thus the network of protoplasm becomes a network of blood-vessels ; the corpuscles and the nuclei of the walls of which have been by separate paths of development derived from the nuclei of the original protoplasm. The formation of the corpuscles does not proceed equally rapidly or to the. Please note that these images
Size: 1509px × 1655px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlondo, bookyear1874
