CHEMISTRY OF RESPIRATION. 
By M. S. Pembrey. 
Contents : — Historical, p. 692 — Respiratory Changes in Air-Methods, p. 694 — 
Conditions affecting Respiratory Exchange, p. 700 — Cold-Blooded Animals, p. 
701 — Fishes, p. 704 — Warm-Blooded Animals, p. 706 — Influence of External 
Temperature, p. 709 — Of Muscular Activity, p. 714 — Of Food, p. 717 — Of Size 
of Animal, p. 720 — Of Time of Day, p. 721 — Of Age, p. 722 — Respiration by 
Skin in Amphibia, p. 723 — In Mammals, p. 725 — Effects of Varnishing Skin, 
p. 727 — Respiration in Alimentary Canal, p. 72* — Respiration of Foetus, 
p. 730 — Of Embryo, p. 733 — The Respiration of different Gases, p. 735 — The 
Respiration of Vitiated Air, p. 741 — Asphyxia, p. 743 — Exchange of Gases 
between Blood and Air, p. 745 — Frequency of Respiration in Man, p. 747 — In 
Animals, p. 753 — Changes in Composition of Air, p. 754 — Effect of Respiration 
on Blood, p. 756 — Gases of Blood- Methods, p. 757 — Arterial and Venous Blood, 
p. 760 — Condition of Gases in Blood, p. 765 — Causes of Gaseous Exchange 
between Blood and Air, p. 773 — Exchanges of Gases between Blood and 
Tissues, p. 780 — Causes of such Exchange, p. 783. 
Respiration is essentially the intake of oxygen and the output of 
carbon dioxide by living cells. In the higher animals two phases of 
respiration are distinguished — the external, the exchange of gases between 
the air or water and the blood; and the internal, the exchange between 
the blood, lymph, and the tissues. 
Historical Acccmnt. 1 — The view held by Aristotle (384-322 B.C.), and 
after him even until the fifteenth century, was that respiration drew air into the 
heart and arteries, and so cooled the blood. Malpigbi (1621-1694) discovered 
the alveoli of the lungs, and saw the blood flowing through the capillaries of 
the alveoli of a frog's lung; and Fracassati, 2 in 1665, noticed that the lower 
layer of a blood clot was much darker in colour than the upper, but that on 
exposure to the air the lower became florid red. Hook 3 showed the following 
experiment at a meeting of the Eoyal Society in 1667. The ribs and diaphragm 
of a dog were cut away, and the trachea connected with a pair of bellows. 
The dog fell into convulsions, but revived when air was blown into the lungs. 
Numerous small holes were now made in the surface of the lungs, and by means 
of two bellows the lungs were kept constantly distended with fresh air ; the 
dog lay still, and its heart beat regularly. A piece of lung was cut off, and it 
was noticed that the blood circulated even when the lungs were collapsed. 
Hook therefore came to the conclusion that the cause of death was not the 
stoppage of the circulation, but the want of a sufficient supply of fresh air. 
Croon 4 had previously shown before the same Society a similar experiment; 
1 For further details see Bostock's "Physiology," 2nd edition, 1828, vol. ii. p. 61; 
Paul Bert, "Lecoris sur la physiol. comp. de la respiration," Paris, 1S70, p. 1; Zuntz, 
Hermann's " Handbuch, " Bd. iv. Th. 2, S. 5. 
3 Phil. Trans., London, 1667, p. 492. 3 Ibid., 1667, p. 539. 
4 Derhani's " Physico-Theology," 4th edition, 1716. p. 140. 
