8 DISTRIBUTION OF HEMOGLOBIN AND ALLIED SUBSTANCES 



note a blue coloration which was subsequently found by Krukenberg (loc. 

 cit.) in specimens of the same species. Rouget (Jour, de la Physiologic, 

 1859, 660) in his studies of the colored corpuscles of the bloods of tunicates 

 and 'Adinozoa found scarlet, orange, yellow, blue, and violet corpuscles. 



The bluish blood of Sepia was noted by Bert (Compt. rend. soc. biol- 

 ogie, 1867, LXV, 300). He showed that the color belongs to the plasma, 

 and 'that it was intensified by exposure to the air, and not destroyed by 

 boiling. Color changes of the same kind were recorded by Rabuteau and 

 Papillon (Compt. rend. soc. biologic, 1873, LXXVII, 135) in the bloods of 

 Octopus and crabs./ They observed not only the effects of the air, but also 

 (of C0 2 , and they discovered the fact that the blue blood does not give 

 spectral absorption bands.,. The statement by Genth that the blue blood 

 of Limulus contains copper received confirmation in the analyses of the blue 

 blood of Helix by Gorup-Besanez (Lehrbuch d. physiologischen Chemie, 

 1878, 379), and by those of Miiller and Schlossberger (quoted by Gorup- 

 Besanez), who found copper in the bloods of Sepia and Octopus. 



Jolyet and Regnard (Archives de Physiologic, 1877, XLIV, 584) found 

 two coloring matters in the blood of crabs, one blue and the other reddish, 

 the former (hemocyanin) being precipitated by alcohol, while the latter 

 (tetronerythrin) remained in solution. They found that agitation of the 

 blood with air developed an ultramarine blue as seen by reflected light, and a 

 brownish coloration as seen by transmitted light, and that upon the removal 

 of O by the gas-pump the blood became rosy and finally yellowish, and that 

 upon shaking the blood with the blue color was restored. In opposition 

 to the statement of Harless and von Bibra (loc. cit.) that CO 2 caused the 

 blood to become blue, they found it to be without influence. They studied 

 the percentages of O, N, and C0 2 (free and combined) in the bloods of 

 crabs, and noted the low capacity for O. In the blood of Astacus they 

 found 3.5 per cent; in the common crab, 3 to 3.2 per cent; and in Pagurus, 

 2.4 to 4.4 per cent of 0. They were the first to suggest that the blue color- 

 ing matter is in protein form. The bloods of Scorpio and Limulus were 

 found by Ray Lankester (Quar. Jour. Microscop. Science, 1878, xxi, 453; 

 1881, xxiv, 151) to become blue upon exposure to the air. 



Tetronerythrin seems to be widely distributed: Merejkowski (Compt. 

 rend. soc. biologic, 1881, xcni, 1029) found it in 104 species, and this list 

 has been largely increased by the investigations of others. 



The term hemocyanin we owe to Fredericq (Bull, de 1'Acad. roy. de 

 Belgique, 1878, xvi, 4; Compt. rend. soc. biolog., 1879, LXXXVII, 996), 

 who definitely showed in the blood of Octopus that the copper, to which the 

 blue coloration is due, is in combination with protein. He recognized the 

 analogy between hemoglobin and its oxide and hemocyanin and its oxide, 

 and that the copper in the hemocyanin molecule plays a similar role to that 

 of the iron of the hemoglobin molecule. He noted that the venous blood was 

 colorless and the arterial blood blue, and that the latter becomes decolor- 

 ized as the weakly combined O is withdrawn in vacua or driven off by C0 2 

 or H 2 S, and that the color is restored by O. The statement of several 

 previous observers that hemocyanin does not give absorption bands was 



