PREVIOUS TO THE INVESTIGATIONS OF PREYER. 89 



states, constitutes, excepting a few traces of other matters, the only con- 

 stituent of the red corpuscles in man and the dog, while in birds and several 

 mammals considerable quantities of albuminous substances are present in 

 the corpuscles. Hemoglobin crystals of bloods of man, the dog, ox, sheep, 

 guinea-pig, rat, mole, hedgehog, mouse, goose, pigeon, hen, frog, adder, and 

 turtle, and probably of the bloods of all vertebrates, he states, contain no 

 other substance than hemoglobin, and particularly is no hematin present 

 in them. 



While Hoppe-Seyler failed to note in his previous research any differ- 

 ence in the spectra of arterial and venous blood, he records that if the 

 solution of hemoglobin is freed from by a current of C0 2 , or by decom- 

 position, it shows a spectrum that is somewhat different from that of a 

 solution that has been shaken with air. He called particular attention to 

 the readiness with which hemoglobin in crystalline form, or in solution, 

 undergoes decomposition. A feeble alkaline reaction of the solution, the 

 presence of albuminous bodies, and a temperature at or below preserve 

 the hemoglobin; but the higher the temperature the quicker the decom- 

 position. No concentrated solution remains undecomposed for 24 hours 

 at ordinary temperature, and, as the spectrum shows, the crystals also 

 become decomposed with like quickness. Dilute solutions are somewhat 

 less readily decomposed than strong solutions. Even dry crystals can not 

 be kept undecomposed, and in the presence of albumin decomposition goes 

 on quickly. In every instance the decomposition of the hemoglobin still 

 present in concentrated solution takes place at first very quickly, and grad- 

 ually less and less rapidly. Therefore, in concentrated solutions, even 

 after many weeks and months, some undecomposed hemoglobin remains. 



In his third contribution (Archiv f. path. Anat. u. Physiologic, 1864, 

 xxix, 597; Centralblatt f. med. Wissensch., 1865, in, 38) Hoppe-Seyler 

 calls attention to the loose combination of with hemoglobin, to the 

 combination of CO with hemoglobin, and to his centesimal analyses of hemo- 

 globin and hematin. His mean figures for the dry hemoglobin of the dog 

 and goose are : 



C 5 4.2H 7 . 2 N 16 Fe .42 



He did not record phosphoric acid and other inorganic constituents, but 

 in later analyses he found phosphoric acid in goose hemoglobin, but not 

 in the hemoglobin of mammals. 



In later publications (Medicinisch-chemische Untersuchungen, 1866, 

 Heft 1, 151, 1867, and Heft 2, 293; 1868, Heft 3, 366, 386) he gives a 

 process for preparing hemoglobin, together with much matter pertaining 

 to the chemistry and to other properties of hemoglobin. His process is as 

 follows : In order to obtain crystals of pure hemoglobin, the blood is defibrin- 

 ated and mixed with 10 volumes of salt solution, which consists of 1 part 

 of saturated solution of chloride of sodium and 9 parts of water, and set 

 aside at until the corpuscles have sunk to the bottom. The supernatant 

 fluid is then drawn off and the corpuscles are washed as often as four 

 times in this way. To the washed corpuscles are added merely enough 

 water to dissolve the hemoglobin and afterwards an equal volume of 



