Of THE FUNCTIONS OF THE LUNGS, 51 



6f copious vapours of phosphorus acid, which could hardly have been the case if the phps* 

 phorus acid had been formed within the vessels, as in this case, it would have remain- 

 ed in solution in the blood, it not being- a volatile substance. It might therefore be sup- 

 posed that the phosphorus was excreted in a state of minute division, from the vessels 

 of the lungs, and meeting, in this state, with the oxygen of the atmosphere, formed the 

 phosphorus acid in question. If this reasoning be admitted with respect to the phos- 

 phorus, it may be extended to the carbon contained in the venous blood. 



From the contradictory eridence on the subject ; from the nature of that evidence ; 

 from the experiments of Dr. Edwards ; from various analogies that might be adduced, 

 could our limits permit, from the conformation of the lungs, and the extent of their 

 excreting and absorbing functions as evinced by experiments ; and lastly, from the con- 

 sideration that, although respiration takes place frequently, yet a very large portion of 

 air remains for a considerable time in the chest, thereby allowing the vitality of the 

 lungs themselves to be exerted upon the air received into them, we conclude that 

 this organ may act in both the ways contended for ; and that, whether it act in one 

 manner or the other, more or less partially, the process is a vital one, and whatever 

 chemical laws may be employed in it, are under the control of the vital influence of 

 the organ, and modified by the ever-varying condition of this influence. 



n. Of Absorption and Exhalation of Jlzote during Respiration. Another subject of 

 much interest connected with the respiratory function, is that which immediately relates 

 to the absorption in the lungs of a portion of the azote contained in the respired air. 

 On this point also, the results of experiments have been various, and opinions respect- 

 ing them equally so. Dr. Edwards of Paris, who is well known as a very intelligent 

 physiologist, concludes, from different experiments, and from the circumstance of the 

 opposite results which they give, some indicating a diminution of the azote of the air, 

 others an increase of it during respiration, that this gas is absorbed into the circulation, 

 and at ter\vards discharged from it ; and that each of these actions is regulated by the 

 constitution, habit, and circumstances of the individual, and by the influence to which 

 he may be subjected, the absorption being to a small extent, while the exhalation is 

 considerable, and vice versa. 



Independently of the satisfactory nature of the experiments whence Dr. Edwards 

 has drawn his inferences, there are many collateral proofs that may be brought to their 

 support, derived from the manifestations of the animal economy in health and disease ; 

 and we have little doubt that not only in azote, but that other gases, even those whose 

 presence in the respired air are accidental, may be also absorbed into, and discharged 

 from the circulation, in a greater or less quantity, according to the varying state or the 

 vital energies of the system. 



III. Of the Jlssintildling Function of the Lungs. The extent of the function of the 

 lungs has been a matter of doubt. Their principal office, namely, that of changing 

 venous into arterial blood, has always been admitted, although the nature of the pro- 

 cess has been disputed. Many physiologists, have in addition to this, attributed to 

 them an assimilating influence which is exerted chiefly upon the absorbed chyle and 

 lymph which the venous blood contains. This opinion appears correct. But the pro- 

 cess is purely a vital one. If the opinion of Dr. Edwards, respecting the absorption 

 and exhalation of azote be correct, this substance may be instrumental in the process. 



A third function has been referred to this organ, viz. the formation of animal heat. 

 But however intimately related it may be with the respiratory process, it cannot be 

 considered a function of the lungs. It must, nevertheless, be allowed that the changes 

 induced upon the blood during respiration, are preparatory to the evolution of animal 

 heat ; and, although we contend that this heat is immediately the result of a manifesta- 

 tion of the vital influence of the ganglial system of nerves, exerted upon the blood 

 contained in the vessels to which these nerves are distributed, yet it must be admitted, 

 that the respraitory processes are requisite to its production, inasmuch as they produce 

 on the blood a change of properties which are requisite to excite this system, and as 

 this fluid, when thus changed, contains the materials necessary to, or is otherwise in a 

 suitable condition for, the manifestation of the influence which the part of this system 

 of nerves which is distributed to the blood-vessels exert. 



