. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. 9° Biology of the Vertebrates surely acts as a deterrent to their spread. Successful invaders that gain a new foothold and retain it catch the eye and claim attention, while unsuc- cessful ones which reach the Promised Land but are unable to establish themselves there, escape attention and pass unnoticed. Many plants that thrive under cultivation, like maize or Indian corn, appear to be unable to maintain themselves in nature when by chance they are allowe
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. 9° Biology of the Vertebrates surely acts as a deterrent to their spread. Successful invaders that gain a new foothold and retain it catch the eye and claim attention, while unsuc- cessful ones which reach the Promised Land but are unable to establish themselves there, escape attention and pass unnoticed. Many plants that thrive under cultivation, like maize or Indian corn, appear to be unable to maintain themselves in nature when by chance they are allowed to run wild. The yellow fever mosquito, Stegomyia fasciata, fortunately does not succeed north of a certain dead-line, although no doubt it has repeatedly crossed this invisible limit, like the English ivy that clothes the walls of southern buildings in luxuriance, but fails to grow well in more northern situations, in spite of being repeatedly planted and nurtured there. 3. Barriers Barriers which check or stop organisms on all sides are at least three in kind: physical, geographical, and biological. Temperature is a widespread physical barrier. The exclusion of "cold- blooded" animals, such as amphibians and reptiles, from the occupation of. HORIZONTAL TRANSITION FROM EQUATOR TO NORTH POLE Fig. 78. Diagram of the general parallel sequence of organisms in alti- tude and longitude. lands of prevailingly low temperatures, is quite evident. In general tempera- ture zones extend not only in latitude north and south from the equator, but also in altitude in a parallel succession from tropical sea level to high mountain peaks (Fig. 78). In the ocean, pressure acts as a barrier that stratifies the inhabitants within certain limits to which they have become specifically adapted. Deep- sea fishes cannot pass freely from abysses to surface waters, nor can pelagic. Please note that these images are extracted from scanned page images that may have been digitally enhanced for
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
