. Elementary biology; an introduction to the science of life. Biology. a By seeing we mean not simply discriminating between light and dark, but being capable of distinguishing forms and colors, as well as light and shade, at some distance. 276. The range of sensitiveness. Some insects, as ants, have shown that they are sensi- tive to other vibra- tions that make no impression at all up- on our retina. We can understand this both from our ex- perience with other senses and from ex- periments. Thus, we know that a blood- hound will percei\e odors that you and I would pass by without notice, and
. Elementary biology; an introduction to the science of life. Biology. a By seeing we mean not simply discriminating between light and dark, but being capable of distinguishing forms and colors, as well as light and shade, at some distance. 276. The range of sensitiveness. Some insects, as ants, have shown that they are sensi- tive to other vibra- tions that make no impression at all up- on our retina. We can understand this both from our ex- perience with other senses and from ex- periments. Thus, we know that a blood- hound will percei\e odors that you and I would pass by without notice, and that even most dogs would not be able to recognize. We know that ordinary dogs will recognize persons by the odor, but that very few human beings are capable of doing so. Again, by means of experiments we have found out that some people can dis- tinguish shades of red or of blue that others cannot recognize at all. We can therefore understand that some nerve end-organs will be sen- sitive to certain colors (rates of vibration) that leave others indifferent. Moreover, some animals are sensitive to light of such low intensity as others would not respond to at all, just as individuals vary as to the quantity of light stimulation necessary to make an ^^>\%^^^. 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 Gruenberg, Benjamin C. (Benjamin Charles), 1875-1965. Boston New York [etc. ] Ginn and company
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