Physiology : A manual for students and practioners / by Theodore C. Guenther and Augustus E. Guenther.

  • Guenther, Theodore C. (Theodore Charles)
Date:
1903
Catalogue details

Licence: Public Domain Mark

Credit: Physiology : A manual for students and practioners / by Theodore C. Guenther and Augustus E. Guenther. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

    33/260 (page 31)
    croiisod inotnbolisiii in (-old wcatlicr, lliiis pi-DviiiLf an cvccjitidii Id the IbiTiioiiiL'' nilc. (irowtli of varioiir^ oriraiiisiiis is <rreatly iiilliiciiced l»y temper- ature. Seeds l)e,ij:iii to germinate only when tlie warmth has reaelied a certain point: tliis for Indian corn is 9° C. ; for tlie date, 15° C Bacterial cultures thrive, likewise, only at definite tcmj)eratures. The tubercle bacillus begins to grow and ])r()f)a- gate at 2<S° ('. The eHect of temperature on ciliary movements can readily be investigated by viewing a portion of the mucous membrane from the (esophagus of the frog under the ndcroscope, and sul)jecting to warm and cold saline solutions. A glass rod, healed to redness and brought against the motor nerve of a frog's muscle, will produce a quick contraction. There are in existence certain vertebrates (proteus) in which the entire skin is KciiKUive to light. This is true to a still greater extent of the onlinary earth-worm. ]>ut among the higher ani- mals the end-organs in the retina are alone clearly responsive to jiliotic stimii/dtloii. It has been found that when the skin is con- stantly ex])Osed to the intense light of the electric arc lamp that the ephhelial cells of the skin undergo a genuine necrosis, which is not brought about by the heat-rays, but by the short waves of the violet end of the spectrum. The stimulating power of light on the chlorophyll-containing bodies of green plants is easily shown for the absorption of carbon dioxide and the formation of starch take jilace only in the presence of light. The rhizojjod pelomvxa responds to sudden illumination in the same manner as it does to any other stimulus—namely, by quickly taking on a spherical form. Certain flagellate and ciliate organisms are also so sensitive to light that they respond by quick movements. The excitation effects of the electrical currents have been inves- tigated most throughly in nerve and muscle. A sudden change in the intensity of a current arouses a nerve impulse in the nerve, and calls forth a contraction of the muscle. An electrical cur- rent, however, stimidates also while it is flowing uninterru])t(Mlly through any living structure. This is shown in nerve by the heightened irritability at the kathode or region where the current leaves the nerve ; in actinospherium, by a disintegration of the organism at the region of the anode, where the current enters the structure and which ceases as soon as the current is interrupted. AmtTcba) and leucocytes witlulraw their pseudopods and become