File:A text-book of physiology for medical students and physicians (1911) (14778976565).jpg

Identifier: textbookofphysio1911howe (find matches)
Title: A text-book of physiology for medical students and physicians
Year: 1911 (1910s)
Authors: Howell, William H. (William Henry), 1860-1945
Subjects: Physiology
Publisher: Philadelphia, London, W.B. Saunders company
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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istry. To ob-tain specimens quickly forexamination under the mi-croscope, one of the mostcertain methods is to takesome blood from one of theanimals whose hemoglobincrystallizes easily, place itin a test-tube, add to it afew drops of ether, shake the tube thoroughly until the blood be-comes laky,—that is, until the hemoglobin is discharged into theplasma,—and then place the tube on ice until the crystals aredeposited. Small portions of the crystalline sediment may then beremoved to a glass slide for examination. According to Reichert,the deposition of the crystals is hastened by adding ammoniumoxalate to the blood in quantities sufficient to make from 1 to5 per cent, of the mixture. Hemoglobin from different animalsvaries not only as to the ease with which it crystallizes, but in somecases also as to the form that the crystals take. In man and in mostof the mammalia hemoglobin is deposited in the form of rhombicprisms; in the guinea pig it crystallizes in tetrahedra (d, Fig. 181),
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Fig. 181.—Crystallized hemoglobin (afterFret/): a, b, Crystals from venous blood of man;c, from the blood of a cat; d, from the blood ofa guinea pig; e, from the blood of a hamster;/, from the blood of a squirrel. GENERAL PROPERTIES: THE CORPUSCLES 423 and in the squirrel in hexagonal plates. In an elaborate and care-ful study of the crystallographic characters of hemoglobin from alarge number of animals Reichert and Brown* have shown thatdifferences exist between the crystals of various species of such acharacter that they may be used to determine whether or notanimals belong to the same genus. This difference in crystal-line form implies some difference in molecular structure, and takentogether with other known variations in property shown by hemo-globin from different animals leads us to believe that the huge mole-cule has a labile structure, and that it may differ somewhat in itsmolecular composition or atomic arrangement without losing itsphysiological property of an oxygen-car

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