298 



Comparative Animal Physiology 



spectra; the mid-points ot some of these absorption bands are given in Table 

 52. Reduced (deoxygenated) hemoglobin has a broad band in the yellow- 

 green, whereas oxyhemoglobin has two principal bands, an alpha band in the 

 yellow, and a beta band in the green. Methemoglobin shows four character- 

 istic absorption bands, of which two are most prominent, a and fi, and the 

 bands of muscle hemoglobin are very close to those of blood hemoglobin. The 

 hemglobins of different vertebrates show qualitatively the same absorption 

 bands; however, it is possible to detect species differences by comparing the 

 extinction coefficients for two maxima. ^*^" Also, in the position of the alpha 

 band of oxyhemoglobin there is a difference of as much as 3 A among several 

 mammals. 



TABLE 51. 



DISSOCIATION (UNLOADING OF OXYGEN) RATES OF BLOOD PIGMENTS 

 ti/ 2 .at=Time in seconds for unloading 50 per cent of O2. 



Table 52 indicates also the absorption bands of hemoglobins (erythrocru- 

 orins) in invertebrate animals. Usually there are two oxyhemoglobin bands 

 (a and yS) and one deoxygenated band which are very similar to the bands of 

 vertebrate hemoglobin. However, differences have been reported as in the 

 location of the bands of carboxyhemoglobin in Arenicola and Cucumaria, and 

 in some annelids and echinoderms the reduced pigment has two maxima. 

 The striking similarity in different animals, however, indicates that the hemin 

 of the body fluids is essentially similar. 



In all of the vertebrate hemoglobins and myoglobins the a band is higher 

 than the (3 band, whereas in the myoglobin of Btisycon, of Ascaris, and of 

 legume root nodules there is more absorption at the /3 than at the a waVe 

 length. The span between the a and /3 bands for blood hemoglobins is 48-56 a, 

 for vertebrate and snail myoglobin 32-36 a, and for Gastrophilus hemoglobin 

 95.5a.»^ 



Molecular Size. Measurements of the molecular weight made by diffusion 

 methods agree well with weights calculated from sedimentation data obtained 



