54 RESPIRATORY EXCHANGE OF ANIMALS AND MAN 



source of error in some of the experiments purporting to demonstrate 

 a formation of fat from carbohydrate. 



Oppenheimer [1909] has made experiments to show that free 

 hydrogen cannot be oxidized in the body of the dog. 



CARBON MONOXIDE. 

 t 



A production of carbon monoxide in the animal body has never 

 been demonstrated or indeed assumed, but experiments have been 

 made by several investigators to see whether it could not be oxidized. 

 It has been found by Haldane [190x3] that it cannot be oxidized by 

 mice.. This result has been confirmed by Weisz [1906] and found 

 to be the same also in rabbits, pigeons and earth-worms ; but Weisz 

 found, contrary to his expectations, that meal-worms, the larvae of 

 Tenebrio molitor, will absorb and probably oxidize notable quantities 

 of carbon monoxide, 7 to 1 5 c.c. per kg. in twenty-four hours. A 

 renewed investigation of this most extraordinary power of oxidation 

 has recently been undertaken by M. Krogh [1915], using very refined 

 methods of analysis. She was unable to confirm Weisz' result and 

 found that carbon monoxide is not attacked at all by the Tenebrio 

 larva or pupa. The respiratory exchange (oxygen and carbon dioxide) 

 is exactly the same in an atmosphere containing 5 per cent, of carbon 

 monoxide as it is in air. 



AMMONIA. 



Several observers have tried in various ways to demonstrate the 

 existence of traces of some highly poisonous organic substance in the 

 expired air of man and mammals. This literature has been critically 

 reviewed by Formanek [1900] who demonstrated the inconclusive 

 nature of the evidence adduced, and found that the substance respons- 

 ible for the observed effects of injecting water condensed from expired 

 air was nothing but ammonia. This gas had also been found in the 

 expired air of man and animals by several earlier observers. The 

 quantities found in the expired air of man are of the order of o to 20 

 mg. in twenty-four hours. Formanek is of opinion that the ammonia 

 when found does not come from the lungs but is a product of 

 bacterial processes in the respiratory tract. This is borne out by 

 the researches of Magnus [1902] who found that the alveolar wall is 

 impermeable to ammonia. 



In certain invertebrate animals ammonia and volatile amines are 

 the chief products of the nitrogen metabolism, and are regularly present 



