The Respiratory Proteins of the Blood. Ii. the Combining Ratio of Oxygen and Copper in Some Bloods Containing Hemocyanin. by Alfred C. Redfield,

The analogy between the transport of oxygen by hemoglobin in the vertebrate blood and by the hemocyanins of the invertebrate body fluids is clearly established. While it is known that in the former case oxygen combines with the respiratory protein in definite stoichiometrical proportions-l molecule of Oa uniting with hemoglobin in correspondence with each atom of iron which it contains (Peters, 1912)-the combining proportion between oxygen and copper in the hemocyanins is not satisfactorily established. Dh6rB (1919) has reviewed the earlier literature in which a general correspondence between the oxygen capacity and copper content of various invertebrat,e bloods is demonstrated, and has presented the first critical experiments based on simultaneous estimations in the same specimens of blood. Dh6r6 found the ratio between the copper and oxygen to be constant in the case of the mollusks (He&z and Octopus) and again in the case of the Crustacea (Astacus, Homarus, and Cancer), but for the same copper content the blood of the Crustacea combined with more oxygen than that of the mollusks. Concerning the validity of this last conclusion Dh6r6 states: “11 serait, croyonsnous, imprudent de l’affirmer en ne disposant que d’une s&ie de d&erminatio& aussi courte. Toutefois, 1’6cart est si notable qu’on ne peut guirre dout.er qu’il n’y ait 18 une difference Aelle. . . . ” In contradiction to this very reserved conclusion Begemann (1924) has found that the blood of the snail (He&x pomatia) and of