194 PHYSIOLOGY. 



For the same substance the bands arc always identical and similarly 

 placed. Thus, a solution of oxyhaemoglobin of a certain strength 

 gives two bands., reduced haemoglobin gives only one. The other 

 derivatives, methaemoglobin, haematin, haemin, etc., though similar 

 to haemoglobin when viewed with the naked eye, yet each gives 

 characteristic absorption bands in various positions. 



Hsemochromogen is produced by treating an alkaline haematin 

 solution with ammonium sulphide. It is reduced alkaline haematin. 



Carbon-monoxide haemoglobin, oxyhaemoglobin, haemochromo- 

 gen, and haematoporphyrin have two characteristic bands in their 

 spectra. 



By adding ammonium sulphide you can distinguish between 

 oxyhaemoglobin and carbon-monoxide haemoglobin, since the two 

 bands of oxyhaemoglobin disappear, whilst those of carboxyhaemo- 

 globin remain unaltered. 



Haemochromogen bands are to the violet side and haematopor- 

 phyrin to the red side of the bands of oxyhaemoglobin in the spec- 

 trum. Acid haematin, alkaline haematin, reduced haemoglobin, and 

 methaemoglobin can each produce a band on the red side of D line. 

 A reducing agent makes this band vanish in the case of methaemo- 

 globin or alkaline haematin, and produces reduced haemoglobin or 

 reduced haematin. Reduced haemoglobin can be temporarily reoxi- 

 dized by shaking the solution. 



Picro-carmine gives a two-banded spectrum, but it differs in 

 position from the double bands of oxyhaemoglobin. They are unal- 

 tered by ammonium sulphide, whilst oxyhaemoglobin gives the double 

 band of reduced haematin by the addition of ammonium sulphide. 



The amount of haemoglobin as calculated by various methods 

 and instruments has been found to be in man, 13.77 per cent.; in 

 woman, 12.59 per cent. Pregnancy reduces the quantity from 9 to 

 12 per cent. Normally there are two periods in a person's life when 

 the amount of haemoglobin attains maximum limits in the blood 

 of the newborn and again between the years twenty-one and forty- 

 five. Pathologically there follows a decrease during recovery from 

 febrile conditions during phthisis, cancer, cardiac disease, chlorosis, 

 anaemia, etc. 



It is known that dry haemoglobin contains 0.4 per cent, of iron, 

 and that all the iron of the blood is held by the haemoglobin of the 

 red corpuscles. The amount of iron in the blood is about 45 grains. 



Colorimetric methods consist in making comparisons between a 

 standard solution of a known strength and the. test solution of blood 



