256 RESPIRATORY FUNCTION OF THE BLOOD 



changes in every other phase. Briefly, blood has an integrative 

 action. 



To come back to the simile of a community : suppose Cotton- 

 opolis failed to function normally. This could be manifested by the 

 scarcity of cotton goods in the hands of the distributors. The 

 cause of the failure might be found by a process of elimination. 

 In general, (1) either the supply of raw material was inadequate 

 (bad harvest or transport strike), (2) or the supply of fuel was 

 restricted (coal strike), (3) or the workers were on strike, or (4) the 

 means of distributing the finished product had broken down 

 (transport strike). It might even happen that (5) over-production 

 had " drugged " the market, producing the invariable reaction on 

 the factory. Similar mishaps might overtake that collection of 

 cell-communities called the animal organism. (1) If the various 

 raw materials are not available even when ample fuel supplies 

 exist, cell life becomes narrowed and inefficient. Certain matter 

 must be imported it cannot be manufactured. If the raw 

 material is imported but does not reach the cell, then the transport 

 system is at fault. (2) A similar statement could be made about 

 the supply of energy. (3) The cell itself may be at fault e.g. after 

 HCN poisoning, in spite of adequate supplies of energy and material, 

 metabolism is at a low ebb. (4) The transport trouble might be 

 due to the scarcity of barges, e.g. anaemia, or to want of force in 

 the driving mechanism, e.g. heart failure. (5) In certain patho- 

 logical conditions a cell-community may take the bit between its 

 teeth and overproduce. The immediate result is to hamper its 

 own activities by the presence of the products of its activity. 



To take a specific instance suppose we find that an organ 

 seems to suffer from a lack of oxygen. This may be due (i) to 

 a scarcity of oxygen in the air breathed analysis will show 

 that, (ii) The lung mechanism may be out of order (Chap. 

 XXVI.). (iii) The membrane separating lung-air from blood 

 may have lost its permeability. Comparison of the oxygen 

 capacity of arterial blood with its actual oxygen content will 

 indicate whether or not this is the fault, (iv) This will also 

 show if the erythrocytes are taking on their full load, (v) If 

 the blood suffers little or no desaturation on passing through the 

 organ, then one may presume either that the haemoglobin has 

 lost its power of unloading oxygen (methaemoglobin) or that the 

 organ has lost the power of using oxygen. Examination of the 

 blood pigment by means of the spectroscope may help us to choose 

 which of these alternatives is correct. 



