ITS PHYSICAL, CHEMICAL, AND STRUCTURAL CHARACTERS. 261 



In other experiments Sczelkow found that the venous blood returning 

 from muscles at rest contained on the average 6.71 per cent, more carbonic 

 acid and 9 per cent, less oxygen than arterial blood, whilst that returning 

 from muscles in action contained an excess of 10.79 per cent, of carbonic 

 acid, and a deficit of from 12 to 14 or even 16 per cent, of oxygen ; and 

 similar results were obtained by Bernard. 1 The experiments of Dr. Gaird- 

 ner 2 seem to show that increase in the relative proportion of oxygen in the 

 blood increases the proportion of fibrin that may be obtained from it, thus 

 the arterial blood of six healthy rabbits furnished the following mean per- 

 centage results, Fibrin 1.65, Corpuscles 82.35, Albumen 46.30. On the other 

 hand, the analysis of the blood of three individuals which had been made 

 to respire pure oxygen for half an hour, gave the following as the propor- 

 tions of its components : Fibrin 2.40, Corpuscles 69.56, Albumen 40.23. It 

 is further stated by Dr. Gairdner 3 that a rabbit having been kept for half 

 an hour under the influence of an electro-magnetic current between the chest 

 and spine, which produced a great acceleration in the respiratory movements, 

 its blood was found to contain as much as 2.9 parts of fibrin in 1000. 4 The 

 larger quantity of fibrin in arterial blood of itself renders its coagulum 

 firmer; but independently of this there would seem to be a difference in the 

 quality of the fibrin, which when separated by stirring or whipping, is more 

 tenacious and compact in arterial than in venous blood. Bert 3 found that 

 when oxygen reaches the proportion of 28-30 vols. for 100 vols. of arterial 

 blood in a dog the animal is seized with convulsions, while a proportion of 

 35 vols. proves fatal. 



195. The proportion of red corpuscles in arterial and venous blood re- 

 spectively has been variously stated by different observers, and we may easily 

 conceive it to be affected by several circumstances, which may produce a 

 change in the whole proportion of the solid to the fluid constituents of the 

 blood during the course of its circulation. Thus, the discharge of the con- 

 tents of the thoracic duct into the venous system near the heart will tend to 

 dilute the blood of the pulmonary and arterial circulation ; whilst conversely, 

 the escape of the watery part of the blood by the renal and cutaneous secre- 

 tions and by transudatiou into the tissues, which takes place during its pas- 

 sage through the systemic capillaries, will tend to augment the proportions of 

 the solids of the blood drawn from the systemic veins. On the other hand, 

 if the discharge of fluid from the thoracic duct be suspended, and the amount 

 absorbed from the tissues during the systemic circulation should exceed that 

 which is transuded (as appears sometimes to happen, 191), then the pro- 

 portion of solid matter will be less in venous than in arterial blood. The 

 difference in the color of arterial and of venous blood is undoubtedly due to 



1 Le9ons, vol. ii, 1859, p. 435. 2 Treatise on Gout, 2dedit., p. 153. 



3 Op. cit , p. 183. 



4 More recently Mr. A. H. Smee (Proceedings of the Royal Society, 1863), and v. 

 Gorup-Besanez (Physiolog. Chemie, 1862, p. 137) have stated that they have obtained 

 a fibrin-like substance; the former, by transmitting Oxygen, and the latter Ozone, 

 through an albuminous fluid. 



5 Comptes Rendus, No. 8 ; Aug. 25th, 1873. 



