BLOOD AND H^EMOPOIETIC ORGANS 79 



a haemorrhage, for the new corpuscles to be loaded up 

 with it, so that one finds that the percentage of haemo- 

 globin in the blood remains low for a considerable time 

 after the red cells have reached their normal number. 

 Long before haemoglobin was known to contain iron, the 

 power of the latter metal as a remedy in some forms of 

 anaemia was well known to physicians ; but the natural 

 inference that such forms of anaemia are due to a deficient 

 supply of iron in the food is not necessarily correct. It 

 would rather seem as if iron, arsenic, and some other 

 metals, have a direct power of stimulating the bone 

 marrow* to increased functional activity. 



Haemoglobin is the mother of pigments in the body. 

 Bile pigment is its direct descendant, and so also is the 

 closely allied or iron-free pigment haematoidin, which is 

 met with at the site of old haemorrhages, such as apo- 

 plectic cysts. 



Hsematoporphyrin is another iron- free derivative of 

 haemoglobin, which is normally produced from the latter 

 in the body in small quantities. In patients who have 

 been taking sulphonal for a long time it is apt to be 

 produced in much greater amount, and gives to the 

 urine a deep port- wine colour, which is always a sign of 

 danger. 



Hsemin, on the other hand, is a purely artificial deriva- 

 tive of haemoglobin never met with in the body, but of 

 great interest and importance as a test for blood in 

 medico-legal cases. 



Methaemoglobin is met with in the urine in small 



* See Stockman, Brit. Med. Journ., 1893, i. 881. 



