A text-book of human physiology / by Dr. Robert Tigerstedt ... tr. from the 3d German ed. and edited by John R. Murlin ... with an introduction to the English ed., by Professor Graham Lusk.

  • Robert Tigerstedt
Date:
1906
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of human physiology / by Dr. Robert Tigerstedt ... tr. from the 3d German ed. and edited by John R. Murlin ... with an introduction to the English ed., by Professor Graham Lusk. 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.

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    organ. It is worthy of note also that the li<rht produced hy the lightning bug is dcficiont at both ends of the spoctruiu. We have here in other words a source of light which is devoid or almost devoid of the ultra-red and ultra- violet rays (Langley and Very). 1. FORMATION OF HEAT Heat is foriued in all dissimilative processes, and since processes of this kind occur everywhere in animate nature, we may say that the generation of heat is universal. This cannot always be demonstrated; for in the isolated elementary organisms the quantity formed is so small that it cannot be meas- ured with our instruments. In plants as a rule heat is formed so slowly that as fast as it is generated, it is radiated to the surrounding medium; consecjuently the temperature of the plant cannot be elevated perceptibly above the medium. It should be said also that the abundant transpiration occur- ring in plants has much to do with keeping down their temperature. The same is true and for the same reason in most of the so-called ruld-blooded or poikjJothermos animals, that is, animals in which the body temperature rises and falls with the temperature of the surrounding medium. In dry air/, on account of evaporation from the surface of the body, the temperature of a cold-blooded animal is usually lower than that of its medium. In a moist or water-saturated atmosphere the body temperature may rise some tenths of a degree. This is true likewise of cold-l)looded animals which live in water. Only in the so-called wann-hJooded or, more correctly, homoiothernios animals (birds and mammals)—i. e., animals whose body temperature remains con- stant in spite of the variations of the surrounding temperature—can the production of heat be demonstrated directly and without difficulty. In these animals the temperature of the body is almost always higher than that of the medium in which they live. I nder certain circumstances it can be shown very clearly that in plants as well as in cold-blooded animals heat is actually formed. With peas which have been allowed to germinate in a funnel under a bel] jar a rise in the temperature of 1.5° C. has been observed. In the spadix of the Aracete (e. g., skunk- cabbage) a temperature of 15° C. higher than that of its surroundings has often been witnessed. Likewise in the fermentation of sugar solutions by the yeast plant elevations of temperature of about the same extent may occur. With regard to the body temperature of the cold-blooded animals, the fol- lowing data on the excess of the animal's temperature over that of its sur- roundings have been gathered: various invertebrates in water 0.21°-0.60 C.; earthworms in a glass vessel 1.4° C.; bees in a beehive 21° C: moving butter- flies 14° C. The animal heat of warm-blooded animals will be more fully discussed in Chapter XIV. J. GENERATION OF ELECTRICITY The enormous number of investigations on animal electricity beo-ins if we except the electrical fishes—with the pregnant observation of Galvani that a frog's thigh contracts when it is touched in two places with the ends of a metallic arc (September JiO, 1786). From this observation Galvani thou^^ht
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