160 HEMOGLOBIN 



side of neutral (^H =11) they avoided mechanical coagulation, as 

 indeed the Oxford workers had done by the addition of ammonia. 



Hitherto this technique has brought us nearer finality chiefly by 

 revealing a fresh source of uncertainty. It would appear that when 

 kept under the most rigorous conditions, i.e. at — 1° C, even a 

 solution of haemoglobin which has been crystallised alters in the 

 following way: the dissociation curve approximates more nearly to 

 a hyperbola as time goes on. Fig. 50 shows the result of time, even 

 in the cold, on such a solution. There are on it two curves, taken 

 from the same solution of haemoglobin, the first 58 hours, the 

 second 5 days after dialysis. It is evident that the double inflection 

 is almost gone from the older haemoglobin. 



The curves drawn represent dissociation curves derived from Hill's 

 equation with values of 1-4 and 1-2 respectively for the "w's" of the 

 less and more "matured" solutions. How like is Fig. 50 to one of 

 our oldest friends — Fig. 51 ! 



REFERENCES 



(1) Douglas, Haldane, J. B. S. and Haldane, J. S. Joum. Physiol, xliv. 276. 



1912. 



(2) BoHB, Hasselbalch and Kbogh. Skand. Arch. f. Physiol, xvi. 390. 1907. 



(3) Parsons, T. R. Joum. Physiol, li. 440. 1917. 



(4) Hastings, Sendeoy, Murkay and Heidelberger. Joum. Biol. Chem. lxi.. 



317. 1924. 



(5) Hartridge and Rotjghton. (As yet unpublished.) 



(6) Barcroft and Murray. Appendix to "Observations upon the Effect of High 



Altitudes,., .chiefly at Cerro de Pasco." Phil. Trans. Roy. Soc. B. ccxi. 

 351. 1923. 



(7) Hecht, Morgan and Forbes. (As yet unpublished.) 



(8) Hartridge and Roughton. (As yet unpublished.) 



