A text-book of physiological chemistry for students of medicine and physicians / by Charles E. Simon.

  • Charles Edmund Simon
Date:
1901
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of physiological chemistry for students of medicine and physicians / by Charles E. Simon. 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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    methods which are- calculated to avoid its chemical alteration. Others, however, have not been successful in repeating his work. The substance which Gautier obtained from spinach-leaves oc- curred in the form of small crystals of a dark-green color, which on exposure to light turned brown, then yellow, and finally became colorless. Its composition corresponded to the formula C^H^NgC^. The mineral ash consisted of about 1.75 per cent, of magnesium phosphate, traces of calcium and sulphates, while iron was absent. Treated with hydrochloric acid, it was decomposed into phylloxanthin and phyllocyanic acid, C19H22N2303 or C,8H20N2O3. This latter is thus a homologue of bilirubin, [C16H18N203]2, which in turn is derived from haematin, and is isomeric with hcematoporphyrin. A most interesting relationship between the blood coloring-matter haemoglobin and the vegetable coloring-matter chlorophyl thus becomes apparent, and constitutes a further link connecting the animal with the vegetable world. Recent investigations have shown that a substance can be obtained from chlorophyl, termed phylloporphyrin, which differs only from hsematoporphyrin anhy- dride in containing three atoms less of oxygen, viz., C32H34N4(32. Both bodies are thus clearly different oxidation-products of one and the same substance. Moderately concentrated solutions of chlorophyl in alcohol or petroleum-ether show seven bands of absorption. The first of these, I, is situated in the red portion of the spectrum between B and C, and is well pronounced and sharply defined on both sides. The bands II, III, and IV are rather indistinct and scattered through the orange-yellow, the yellow and the yellowish-green portion be- tween C and E. From F off, the greater portion of the spectrum is absorbed by the remaining bands, V, VI, and VII, of which V is seen to the right of F, VI most marked about C, while VII occu- pies the extreme violet end. Very concentrated solutions allow the red rays to pass only as far as B, while in greater dilution the green rays likewise appear. Such solutions, therefore, appear green when viewed with transmitted light, while with reflected light they are red and fluorescent. When a fresh leaf is similarly examined, a spectrum is obtained which is essentially the same as that just described. There is lack- ing, however, the band that corresponds to the red fluorescent rays of chlorophyl solutions. This is explained by the assumption that the red rays are absorbed by living chlorophyl and transformed into chemical energy. In accordance with this view, we find that when living plants are successively exposed to the various rays constitut- ing sunlight, decomposition of carbon dioxide with liberation of oxygen—which, as we shall presently see, takes place in the green portions of every plant whenever it is exposed to sunlight—occurs with special intensity when the plant is exposed to the rays corre- sponding to the bands I, II, and III. In this manner, then, chloro- phyl-bearing plants derive their kinetic energy from sunlight, and
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