OF HEMOGLOBIN, AND ITS SPECIFICITIES. 69 



that by mixing the pulp with an isotonic salt solution the hemoglobin was 

 dissolved. This he holds would not occur " if the hemoglobin was in com- 

 bination with the stroma. " However, his method may have been the 

 means of breaking up a hemoglobin-stroma union. Moreover, Stewart 

 (see below) has found, in his experiments on the influences of various agents 

 on the osmotic properties of the erythrocytes, that the hemoglobin can 

 not exist in the corpuscles in ordinary aqueous solution. 



Hoppe-Seyler (Physiologische Chemie, 1877, 381; Zeit. f. physiolog. 

 Chemie, 1889, xm, 477) attempted to show, by various facts and arguments, 

 that such differences exist between the behavior of the coloring matter of 

 the blood as it exists in corpuscles and hemoglobin in solution that they can 

 not be identical. Most of his deductions have, however, been found to be 

 untenable. He distinguishes between the coloring matter of the blood, 

 oxyhemoglobin, and reduced hemoglobin, regarding both oxyhemoglobin and 

 reduced hemoglobin as cleavage products. He looks upon the " coloring mat- 

 ter" of the blood as consisting of combinations of oxyhemoglobin and hemo- 

 globin with lecithin, forming firm chemical unions. The coloring matter of 

 arterial blood he distinguishes as arterin and that of venous blood as plebin, 

 the only difference between these two substances being a feebler combina- 

 tion of oxygen in the former. While Hoppe-Seyler's hypothesis seems to 

 have received a tacit acceptance, it has been opposed by Gamgee (Scha- 

 fer's Text-book of Physiology, 1898, 1, 190) and questioned by others as 

 being untenable ; but it has been defended by Robert (Das Wirbeltierblut, 

 etc., Stuttgart, 1901, 5). 



Bohr (Zentralbl. f. Physiologic, 1904, xvn, 682, 688) believes that the 

 coloring matter of the blood, which he terms hemochrome, is not identical 

 with hemoglobin (which he prepared without the addition of alcohol), 

 because the latter has a lower oxygen capacity. 



Recent evidence that hemoglobin exists in the corpuscles in some 

 peculiar form of combination has been recorded by a number of investi- 

 gators. Thus, Stewart (Journal of Physiology, 1899, xxiv, 211; Amer. 

 Journal of Physiology, 1902, vm, 103) found, in a very interesting study of 

 the effects of taking agents, " that the relations of the hemoglobin and the 

 electrolytes of the corpuscle to some of the other constituents of the cor- 

 puscle or to the envelop are such that under certain conditions hemoglobin 

 may be liberated while the electrolytes are retained; while under other 

 conditions electrolytes may pass through an envelop which refuses passage 

 to the hemoglobin, although in general it is easier for the hemoglobin, in 

 spite of the great size of the molecule, to escape from the corpuscles than 

 it is for the electrolytes. " He also found that, while hemoglobin may pass 

 from the corpuscle, hemoglobin dissolved in the serum would not pass into 

 the corpuscle. In explanation of these phenomena Stewart proposes 

 four hypotheses as to the condition of the hemoglobin and the electrolytes 

 in the corpuscles: 



(1) A portion of the electrolytes and of the hemoglobin is in solution 

 as such; and the rest is in solution as compounds with other substances, 

 such compounds being unable to pass through the envelop. 



