362 î*- J- Anderson, 



99 mm. of Mercury, or 13 per cent of an atmosphere, whilst 38.5 per 

 cent of an atmosphere was calculated for the Arterial blood of man, 

 17.6 — 24 p. c. for the dog, 44 per cent for birds. There is a small 

 amount of carbonic oxide in normal blood (1.5 p. c.) but in Haldane 

 and Smith's experiments the blood contains 30 — 80 per cent. It is 

 known that Haemoglobin is associated with some other constituent 

 of the Corpuscles, hence although the percentage is established by the 

 spectrophotometer the nature of the compound may not be so well 

 established. The Carbonic Oxyde (C. 0.) is oxidized during the experi- 

 ments according to St. Martin, at all events the conditions of Meta- 

 bolism may to some extent be changed. The tensions of the oxygen 

 in the different experiments vary greatly at different times, so that 

 16, 26, and 38 per cent have been obtained. 



The Chemical affinity of the Haemoglobin leads to the absorption 

 of oxygen by lowering the tension of that gas in the plasma, so that 

 air enters the blood from the air cells by diffusion to replace the 

 oxygen taken up by the Haemoglobin. In a diffusion (Osmosis) experi- 

 ment Sodium chloride will be attracted from its solution in the outer 

 vessel by gelatine in the inner (Ver worn) so will Methyl violet (Hof- 

 meister). 



The air cell endothelium is regarded as a not unimportant factor 

 in the promotion of gaseous interchange. The living protoplasm of 

 the endothelial cells is an important factor in the secretion of urine 

 and the discharge of lymph. It has been proved by Regnard and 

 Schloesig that the amount of Argon and Nitrogen in the blood is 

 much greater (nearly double) than it would be in solution, and they 

 are of opinion that the alveolar membrane takes an active part in 

 causing a solution of abnormal quantities. Pflüger has shown that 

 no oxygen is discharged into the alveoli when Hydrogen or Nitrogen 

 is breathed. Haldane and Smith found that the tension of the oxygen 

 in arterial blood varied in pathological states of the lungs, fevers &c. 

 during great diminution in the tension of the air breathed. 



The air of the Air bladder in Fishes contains oxygen, nitrogen, 

 and possibly argon, which seem to be secreted like Saliva under the 

 influence of the nervous system, while the fresh wall of the bladder 



