CHANGES IN AIR AND BLOOD IN RESPIRATION. 667 



to this supposed substance. The investigations that have been 

 made upon this substance are, unfortunately, far from being 

 conclusive.* It seems to be clear that, when the expired air is 

 condensed by passing it into a cooled chamber, the water thus 

 obtained, about 100 c.c. for 2500 liters of air, is clear, odorless, and 

 has only a minute trace of organic matter. If this liquid with or 

 without condensation is injected under the skin or into the blood- 

 vessels no evil result follows, according to the testimony of the 

 majority of observers. But it remains possible, of course, that the 

 substance if present may be destroyed by this method or may es- 

 cape precipitation in the condensed water. An experiment that 

 was supposed to give a positive indication of the existence of an 

 organic (basic) poison in the expired air is the following, first per- 

 formed by Brown-Sequard : A series of say, five bottles, each 

 of a capacity of a liter or more, are connected together in train so 

 that air can be drawn through them by an aspirator. A live 

 mouse is placed in each bottle, and between bottles 4 and 5 an 

 absorption tube is arranged containing sulphuric acid. Under 

 these conditions only the mouse in bottle 1 gets fresh air, those in 

 the successive bottles get more and more impure air, while in bottle 

 5 this air is purified to the extent of removing the organic matter 

 by passing it through sulphuric acid. The result of such an ex- 

 periment as described by some observers is that the mouse in bottle 

 4 dies after a certain number of hours, the one in bottle 3 later, 

 while those in the first and last bottles show no injurious effects. 

 The obvious conclusion is that death in such cases is due to some 

 organic toxic substance, and not to a mere increase of carbon 

 dioxid, chemical analysis showing that this latter substance does 

 not accumulate sufficiently under these conditions to cause a fatal 

 result. Some other observers have failed to get this effect, but 

 even assuming it to be correct it will be noted that the experiment 

 gives no proof that the organic substance in question is excreted 

 in the expired air. Indeed, the seemingly very careful experiments 

 of Formanek make it probable that in these experiments the toxic 

 substance is ammonia or an ammonia compound, which is not 

 given off from the lungs, but from the decomposition of the urine 

 and feces in the cage. When this latter source of contamination 

 is removed the expired air is practically free from ammonia and 

 without injurious effect. The expired air, therefore, according to 

 work of this character, contains no organic poison which can be 

 regarded as a product of respiration. 



* See Haldane and Smith, "Journal of Pathology and Bacteriology," 

 1, 168 and 318, 1893; Merkel, "Archiv f. Hygiene," 15, 1, 1892; Formanek, 

 "Archiv f. Hygiene," 38, 1, 1900; Weichardt, ibid., 65, 252, 1908. Amoss, 

 "Journal of Exp. Medicine," 17, 132, 1913. 



