24 DISTRIBUTION OF HEMOGLOBIN AND ALLIED SUBSTANCES 



like nature in relation to the globin and stroma. It has, moreover, been 

 suspected, and even asserted, that the respiratory property of the eryth- 

 rocyte, in so far as the give-and-take of and CO 2 is concerned, is inten- 

 sified by or even dependent upon the cooperation of an oxidase in the 

 blood corpuscles or blood plasma. Here we have a paraUel to the influence 

 of phycoerythrin upon the energy of chlorophyl. 



The absorptive and carrying property of hemoglobin in relation to O 

 has been and continues to be attributed to the atom of iron in the molecule, 

 and this assumption has been applied to the metal components of other 

 respiratory substances, but upon very limited and inconclusive although 

 seemingly plausible data, which in a word are virtually the affinity and 

 capacity of iron. 



The absorption coefficient of hemoglobin of the bullock for oxygen 

 has been determined experimentally by Htifner to be 1.34 c.c. at C. and 

 760 mm. pressure, which figure is practically identical with the capacity 

 as estimated by the percentage of iron (0.336) present; hence, the natural 

 conclusion and the universally accepted view that the property and capacity 

 of hemoglobin in relation to O is specific to the atom of iron. The fact, 

 however, should not be lost sight of in this connection that the absorptive 

 capacities, as determined by different investigators, are by no means in 

 accord. Thus, reducing all figures to and 760 mm., the values are, 

 according to Dybkowsky, 1.57; Hoppe-Seyler, for moist crystals 1.09, for 

 crystals dried at room temperature 0.77, and for crystals dried at and 

 powdered 0.54; Strassburg, 0.45 to 3.88; Preyer, 1.72 and 1.8; Worm-Muller, 

 1.38; and Hiifner, 1.59 and 1.34 (latest). Even Hiifner's latest figures vary 

 as much as 10 per cent, and his corrections are not beyond reasonable 

 question. It is, moreover, doubtful if the property thus attributed to 

 the metal, or even to the hematin, is justified, for while the quantitative 

 relation of the oxygen capacity to the quantity of iron seems convincing 

 as an isolated fact, the deduction is not borne out by our knowledge of this 

 and other respiratory bodies and by other facts. After all, the absorption 

 capacity is merely the maximal capacity for oxygen that can be observed 

 under given conditions of pressure and temperature, other things being 

 equal; moreover, this assumed specificity of the metal of the molecule is 

 scarcely reconcilable with the fact of the existence of metal-free respiratory 

 substances (achroglobulins) which have practically identically the same absorp- 

 tion capacities as hemoglobin. This quantitative coincidence of the 0- 

 capacity of hemoglobin and achroglobulin is certainly remarkable, and it 

 shows clearly either that the specificity attributed to the iron is wrong, or 

 that we have a substitute in the achroglobulin which has the same quanti- 

 tative value as an absorptive factor, but this is hardly credible. If the 

 accepted specificity of the iron be justified, we still have to find an explana- 

 tion for the practically absolutely identical 0-capacity of the metal-free 

 achroglobulins. 



Then again, assuming that the metal is the specific 0-absorbing agent, 

 hemocyanin should have an absorptive capacity, based upon the percent- 

 age of copper present, of 0.66 c.c. per gram at and 760 mm., while in 



