A MANUAL OF VETERINARY PHYSIOLOGY 



pig readily yields crystals of oxyhemoglobin ; that of the ox, 

 sheep, and pig crystallises with difficulty. The crystals are 

 generally rhombic prisms or needles, but the form differs according 

 to the animal (Fig. 3). Reduced haemoglobin can only be crystal- 

 lised with great difficulty, and in an atmosphere free from oxygen 

 The total amount of haemoglobin in a horse's body is about 

 4 kilogrammes (88. pounds), and the amount of iron contained 



in this is about 17 grammes 

 (257 grains). This calcula- 

 tion is based on the assump- 

 tion that the amount of 

 blood in the body is 29 

 litres (50 pints). 



In the dried red blood- 

 cells haemoglobin exists in 

 the proportion of 90 to 94 

 per cent., in the corpuscle 

 under normal conditions it 

 represents 32 per cent, of 

 its weight; while in the 

 total blood of the horse it 

 forms 13*15 per cent., in 

 the ox 9-96 per cent., sheep 

 10-34 per cent., pig 12*7 per 

 cent., and dog 9-77 per 

 cent. (Ellenberger).* The 

 younger the animal the less 

 haemoglobin ; males have 

 more than females, and cas- 

 trated animals more than 

 entires (G. Muller).f 



Methaemoglobin is a deri- 

 vative of haemoglobin, and 

 may be produced by allow- 

 ing blood to be exposed to 

 the air until it becomes 

 brown in colour and acid 

 reaction ; or it may be prepared by the action of acids or 

 alkalies on oxyhaemoglobin. This substance contains the same 

 amount of oxygen as haemoglobin, but it will not part with it, 

 excepting in the presence of reducing agents ; for respiratory 

 purposes it is therefore useless. It is not a normal constituent 

 of the blood, but may be found in the urine whenever a sudden 

 breaking-down of red corpuscles occurs, as, for example, in the 

 so-called azoturia of the horse. Its spectrum is seen in Fig. 2. 

 * ' Physiologie der Haussaugethiere.' t Ibid - 



Fig. 3. — Oxyhemoglobin Crystals. 



a, b, From man ; c, from cat ; d, from guinea 

 pig ; e, from hamster ;/, from squirrel (Frey). 



in 



