. Agricultural zoology. Zoology. INTRODUCTION. 13 The blood is the fluid into which the food-stuffs are taken up. It consists of an almost colourless liquid, together with an innumera,ble number of exceedingly- minute blood-corpuscles. The blood flows through the body in a system of tubes, or blood-vessels, which branch repeatedly, and at last become merged in the microscopic capillary blood-vessels. These capillaries are present in nearly all parts of the body except the epidermis and epi- dermal structures (hairs, feathers, scales, etc.). They have exceedingly thin walls, which present no re
. Agricultural zoology. Zoology. INTRODUCTION. 13 The blood is the fluid into which the food-stuffs are taken up. It consists of an almost colourless liquid, together with an innumera,ble number of exceedingly- minute blood-corpuscles. The blood flows through the body in a system of tubes, or blood-vessels, which branch repeatedly, and at last become merged in the microscopic capillary blood-vessels. These capillaries are present in nearly all parts of the body except the epidermis and epi- dermal structures (hairs, feathers, scales, etc.). They have exceedingly thin walls, which present no re- sistance to the passage of the nutritious substances contained in the blood, so that these can be absorbed by those parts of the body which lie between the individual capillary vessels. The central organ of the circulation is the heart, an enlarged part of the vascular system, possessing thick muscular walls. By con- traction of these, the blood is driven out of the heart (Fig. 6, H); and its exit is possible on one side only (a), as at the other side (&) there is a valve, which closes when the heart contracts. The vessel into which the blood leaving the heart enters is termed an artery () It divides into several branches, also known as arteries, and the smallest arteries pass into capillaries, which again are connected with veins, which join larger and larger veins, until finally one or a few open into the heart (A).. Fig. 6.—Diagram of the Courae of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bos, Jan Ritzema, 1850-1928; Ainsworth Davis, J. R. (James Richard), 1861-1934. London, Chapman & Hall, Ld.
Size: 1337px × 1868px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1894
