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adult anterior aorta aperture appears arch archenteron arises arranged artery articulation atrial auditory becomes blood body bones brain branch branchial called canal capsule cartilage caudal cavity cells close communicates completely connected consists containing continuous cord covered Craniata developed differ divided divisions dorsal duct ectoderm elongated embryo epithelium extends external Fishes fold forwards front gills gives gland head heart Including internal intestine kidney lateral layer lobes longitudinal lower median membrane middle mouth muscles narrow nerve notochord olfactory opening optic oral organ origin paired passes pelvic pharynx placed plate portion position posterior present region remains represented ridge runs segmentation separated short side single sinus situated skull sometimes spinal stomach structure supply supported surface tail teeth tissue transverse trunk tube upper usually vein ventral ventricle vertebral vessels wall Zootomy
Page 350 - ... would it be too bold to imagine, that all warm-blooded animals have arisen from one living filament, which THE GREAT FIRST CAUSE endued with animality, with the power of acquiring new parts, attended with new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down those improvements by generation to its posterity, world without end!11 Vegetable life he believes...
Page 340 - The range of variation is so great among Foraminifera as to include not merely the differential characters which systematists proceeding upon the ordinary methods have accounted specific, but also those upon which the greater part of the genera of this group have been founded, and even in some instances those of its orders.
Page 355 - ... stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position— namely, at the close of the Introduction — the following words: "I am convinced that natural selection has been the main but not the exclusive means of modification.
Page 350 - ... would it be too bold to imagine, that in the great length of time, since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, would it be too bold to imagine that all warm-blooded animals have arisen from one living filament...
Page 21 - Planaria the head has a relatively high rate of metabolism and dominates the rest of the body. Experiments have shown that a gradient of metabolic activity proceeds from the anterior to the posterior end. For example, if planarians are cut into...
Page 350 - ... shall we conjecture that one and the same kind of living filament is and has been the cause of all organic life ? * ******
Page 355 - Are those divisions artificial or natural ? Are they the devices of the human mind to classify and arrange our knowledge in such a manner as to bring it more readily within our grasp and facilitate further investigations, or have they been instituted by the Divine Intelligence as the categories of his mode of thinking?
Page 350 - And here we must in the first place admit that he was the first who proposed and consistently carried out, a wellrounded theory with regard to the development of the living world, a merit which shines forth most brilliantly when we compare with it the vacillating and confused attempts of Buffon, Linnaeus and Gothe.
Page 129 - ... bulbus. A fraction of a second is, however, enough to get up the pressure in the pulmonary and cutaneous arteries, and in the meantime the pressure in the arteries of the head, trunk, etc., is constantly diminishing, owing to the continual flow of blood toward the capillaries.
Page 355 - ... reason, have we followed only, and reproduced, in our imperfect expressions, the plan whose foundations were laid in the dawn of creation, and the development of which we are laboriously studying, — thinking, as we put together and arrange our fragmentary knowledge, that we are introducing order into chaos anew?