646 EXPERIMENTAL INVESTIGATION OF THE ACTION OF MEDICINES. 



internal respiration is imperfect, the nitrogenous substances 

 may not be oxidised, and appear in the urine instead of being 

 converted into urea. The non-nitrogenous substances may 

 also continue unoxidised, and, instead of being converted into 

 carbonic acid, remain in the tissues as fat, giving rise to fatty 

 infiltration or fatty degeneration. This is seen in the heart 

 when the size of the coronary arteries is diminished by 

 atheroma. The supply of blood being insufficient to keep up 

 perfect combustion in the muscular fibres, the non-nitrogenous 

 products of decomposition accumulate and cause the heart to 

 become fatty. 



When there is little haemoglobin in the blood, as in anaemia, 

 internal respiration is diminished, and there may frequently 

 be noticed a tendency to the deposit of fat in anaemic girls. 

 The peasantry in some parts of Germany are acquainted with 

 this fact, and bleed their cows so as to induce an artificial 

 anaemia whenever they wish to fatten them. 



2. Internal respiration may be arrested by the action of 

 substances which deprive haemoglobin of its power to take up 

 and give off oxygen easily, and thus render it useless as an 

 oxygen-carrier, a. Certain gases — for example, carbonic oxide 

 and nitric oxide — do this by driving out the oxygen from its 

 combination with haemoglobin, and forming compounds with 

 it themselves. These compounds resemble those with oxygen, 

 but are more stable, and are not decomposed during the 

 passage of the blood through the capillaries, nor by the action 

 of reducing agents added to the blood, as oxyhaemoglobin is. 

 h. The oxygen-carrying power of haemoglobin has been shown 

 by Dr. Arthur Gamgee to be also destroyed by nitrites, but 

 in a different way. Instead of driving out the oxygen from 

 its combination with haemoglobin, the nitrites combine with 

 the oxyhaemoglobin, and as it were lock up the oxygen in it, 

 so that the oxygen no longer separates from the haemoglobin 

 when the compound is placed in a vacuum, nor can it be 

 driven out by the action of carbonic oxide. At the same time, 

 the blood which has been acted on by nitrites is deprived of 

 its power of absorbing any more oxygen. But, although the 

 nitrites lock up the oxygen in oxyhaemoglobin so firmly that 



