434 Historical 



30. On return to normal air, the tracing gradually regains its 

 original form. 



31. The radial pulse seems changed to the touch; it becomes 

 small, filiform, almost imperceptible. 



32-33. These sections relate to an experiment which will be re- 

 ported in the following chapter. 



34. The action of the heart in compressed air is not stronger; 

 but we do not know whether it diminishes, although that is probable. 



35. The sphygmographic curve, while the pressure is increasing, 

 is above that obtained in normal air. There is, therefore, in this 

 phase an increase in the total pressure of the blood, at least in the 

 radial artery. 



36. Experiments made on animals, on the pressure of the 

 blood in the carotid artery, by means of the hemo-dynamometer gave 

 no result. It is probable that when the air pressure has become 

 constant, a new degree of equilibrium is reached, the action of the 

 heart which has become less strong brings a decrease in the aortic 

 system. 



37. The decrease in caliber of the vessels of the conjunctiva, 

 of the retina ,and of the ears of rabbits, the loss of color in the 

 pupil and the iris of white rabbits, the pallor of workmen who 

 labor in compressed air, directly prove the ebbing of the blood from 

 the periphery towards the center. 



38. Thence come the decrease, of the intra-ocular pressure, 

 the contraction of the pupil, the lessened sensation of the pulse in 

 the ear and the jaw, the decrease of the redness in the membrane of 

 the tympanum, the improvement in cases of erysipelas, and finally 

 the decrease in size of scrofulous strumae. 



39. A manometer placed in the jugular vein showed that the 

 venous pressure diminishes in compressed air. (Vivenot did not 

 make any experiments on this; he depends upon an experiment of 

 Panum, which he himself finds unsatisfactory and poorly carried out. 

 (P. 414). 



No direct experiments have been made in regard to the effect 

 of compressed air upon the venous and lymphatic systems. But 

 it is certain that it can only be stimulating; moreover, the negative 

 pressure, which is increased, acts also on the heart and the large 

 vessels. 



40. The temperature in the armpit increases while the air is 

 being compressed, it reaches its maximum with the compression. Dur- 

 ing the stage of constant pressure, there is also an increase of rectal 

 temperature. 



41. It is shown by our experiments that a part of the blood is 

 driven back from the periphery of the body; the organism has there- 

 fore at its disposal a quantity of blood which must rush to the organs 

 which are more deeply situated, such as the brain, the spinal cord, the 

 muscles, the alimentary canal, the liver, the spleen, the kidneys, and 

 the uterus. Thence result, for the brain, the heaviness of the head, 

 the slight deafness, and the yawning; for the alimentary canal, the 

 hunger and the increased rectal temperature; for the muscles, the 

 increase of muscular energy and of the axillary temperature; for the 



