294 Comfarative Animal Physiology 



Mammalian erythrocytes are approximately 32 per cent hemoglobin, 60-65 

 per cent water, and about 8 per cent stroma, consisting of lecithin, cholesterol, 

 inorganic salts, and protein. In fetal life the red blood cells are manufactured 

 in liver and spleen; in adults they are made largely in the bone marrow. Red 

 blood cells are subject to severe wear and tear and survive only a few weeks in 

 the open circulation. Measurements made with radioactive hemoglobin indi- 

 cate the mean life of the red cell in the dog to be about 100 days;^' in the 

 chicken the lifetime of the red cell is about 32 days, by measurements made 

 with P^- in the nucleic acid.^^" 



TABLE 49. DISTRIBUTION OF RESPIRATORY PIGMENTS IN POLYCHAETE, 



SIPUNCULOID AND ECHIUROID WORMS 



(Modified and extended from^''^) 



Closed circulatory system 



Coelomic Huid pigmented 



Hemoglobin in cells of coelomic fluid and in blood plasma 



Terebella lapidaria Travisia forbesii 

 Coelomic fluid not pigmented 



Hemoglobin in blood plasma 



Nereidae Arenicola marina Amphistenidae 



Amphitrite rubra Clymene lumbricoides Cirratulidae 



Pista cristata Eunicidae 



Chlorocruorin in blood plasma 



Sabellidae Serpulidae Chlorhaemidae 



Hemerythrin in non-nucleated blood corpuscles 



Magelona papillicornis 

 No pigment in either blood or coelomic fluid 



Syllidae Aphroditidae Lepidonotus squamatus 



Phyllodice Chaetopteridae 



Circulatory system lacking or degenerate, blood not pigmented 

 Hemoglobin in corpuscles in coelomic fluid 



Capitellidae Polycirrus hematodes Urechis caupo 



Glyceridae Polycirrus aurantiacus Thalassema neptuni 



Hemerythrin in corpuscles in coelomic fluid 



Sipunculus nudus Phascolosoma. 



No pigment in coelomic fluid 



Polycirrus tenuisetis Polycirrus arenivorus 



CHEMISTRY OF PIGMENTS 



Hemoglobin: Chemical Cotnposition. The molecules of hemoglobin are 

 large, and consist of a protein, globin, and pigment, hemin. Hemin is the 

 hydrochloride of heme, a metaloporphyrin. Porphyrins are composed of four 

 pyrrol rings, as shown in Figure 66. Other metals than iron can combine with 

 porphyrin; for example, the pigment in the feathers of the South African 

 turaco is a combination of porphyrin and copper. Heme can combine with 

 various nitrogenous compounds to give hemochromogens. A hemochromogen 

 can be produced by the action of acid or alkali upon hemoglobin. The most 

 widespread of all hemochromogens is cytochrome, a respiratory pigment which 

 occurs in three forms, a, b, and c, and is found in most, if not all, aerobic 

 cells.''-'* Other hemochromogens are such pigments as actiniohematin, which 

 occurs in sea anemones, and helicorubin, which is found in the muscles and 

 bile of certain snails.'"' ''" The heme in all these hemochromogens is similar; 



