96 PHYSIOLOGICAL CHEMISTRY. 



by keeping the blood or its solutions protected from the access of air. 

 The last method is most easily applied. If a solution of fresh blood, 

 of a bright scarlet color, which yields a spectrum with the absorption 

 bands of oxyhemoglobine fully developed, be inclosed in a securely 

 stopped test-tube, the whole of which it completely fills, and kept in 

 this condition for twenty-four or forty-eight hours, the hemoglobine at 

 the end of that time will have lost its surplus oxygen, and if placed 

 before the spectroscope, the solution will show a spectrum with the 

 single absorption band of reduced hemoglobine. If the test-tube be 

 now opened, the solution transferred to a larger vessel, and shaken up 

 for a few seconds with atmospheric air, its bright color returns, the 

 single absorption band disappears from its spectrum, and the two 

 absorption bands of oxyhemoglobine again become visible. 



The spectroscopic characters of hemoglobine arc of value in showing 

 that this substance, as extracted in the crystalline form, is identical 

 with the normal coloring matter of the fresh globules. A solution of 

 crystallized hemoglobine gives the same spectrum with solutions of 

 fresh blood or with the dried globules. The blood, while still circulat- 

 ing in the vessels, may also be made to exhibit the same appearances. 

 If a spectroscope eye-piece with two prisms be attached to the body of 

 a microscope in such a way that two spectra may be seen in the field, 

 one above another, one formed by the light coming through the body 

 of the instrument, the other by that coming through a lateral opening 

 in the eye-piece ; and if the mesentery of a living frog be placed 

 before the objective of the microscope, while a solution of human blood 

 is placed at the lateral opening, it will be seen that the absorption bands 

 in the two spectra correspond exactly with each other. 



The hemoglobine from different animals varies somewhat in the form 

 of its crystals, in their degree of solubility in water, and, according 

 to several analyses, in the exact percentage of its constituent elements. 

 But its spectroscopic characters are remarkably invariable ; and their 

 immediate connection with its essential physiological property, namely, 

 the absorption and discharge of oxygen, shows them to be the most 

 important marks for its identification. By this means the existence 

 of hemoglobine in the blood-globules has been demonstrated in such 

 different animals as the dog, fox, cat, horse, sheep, pig, lion, cougar, 

 baboon, bat, hedge-hog, rat, guinea-pig, squirrel, mole, goose, pigeon, 

 lark, owl, crow, lizard, python, tortoise, frog, carp, perch, herring, and 

 pike. It has been discovered, in all, in 22 species of mammalians, t 

 birds, 5 reptiles, and 12 fish ; and exists in every species of vertebrate 

 animal which has been examined for that purpose. Even in several 

 invertebrate species, where the blood is of a red color, although exhibit- 

 ing no distinct globules, it is found to contain hemoglobine in a state 

 of solution. Preyer found that the red circulating fluid of the earth- 

 worm, when examined by the spectroscope, yields a spectrum with 

 two absorption bands identical with those of human hemoglobine. It 



