TRANSFUSION OF BLOOD. 



This marked fall, which is not accompanied by a corresponding fall in the pressure, 

 is attributed by v. Kries to a peripheral reflection, that is, one in which a positive 

 wave is reflected as such. The dicrotic elevation (secondary wave) appears, further, 

 somewhat earlier in the plethysmographic curve (current-pulse) than in the 

 sphygmographic curve; although it also has a centrifugal course, as in the sphyg- 

 mo graphic curve. 



2. The respiratory fluctuations, which correspond to the respiratory fluctua- 

 tions in blood-pressure. Active breathing and cessation of breathing produce a 

 diminution in volume. Further, the part has been observed to undergo enlarge- 

 ment in consequence of effects at bearing down and coughing, and reduction in 

 size during sobbing. 3. Certain periodic fluctuations, dependent upon periodic- 

 regulatory movements of the vessels, particularly of the smaller arteries. 4. Vari- 

 ous fluctuations due to accidental causes that bring about alterations in the 

 blood-pressure, such as change of position producing hydrostatic effects; dilatation 

 or contraction of other large vascular areas. 5. Muscular movements in the ex- 

 tremity introduced into the plethysmograph cause a reduction in volume, because 

 the venous pulse is accelerated, and in addition the musculature itself is somewhat 

 reduced in size, in spite of the fact that the intramuscular vessels are dilated. 



6. High (from 33 to 36 C.) and low (from 4 to 8 C.) temperature, when 

 applied to the skin of the arm, increase the volume of the member in consequence 

 of paresis of the muscular coat of the blood-vessels caused by the thermic stimuli. 



7. Mental exertion diminishes the volume of the extremity; sleep has the same 

 effect. 8. Compression of the afferent artery causes diminution, while constriction 

 of the veins naturally causes an increase in the volume. 9. Irritation of the vaso- 

 motor nerves is followed by a decrease, that of the vasodilators by an increase, 

 in volume. 



TRANSFUSION OF BLOOD. 



Transfusion is the physiological introduction of blood into the vascu- 

 lar system of a living being. 



The first mention of direct exchange of blood between two individuals from 

 vessel to vessel takes us back to the time of Cardanus. After the discovery of 

 the circulation of the blood, Potter in England again called attention to the prac- 

 ticability of transfusion. Numerous experiments were made on animals. Attempts 

 were made by the introduction of fresh blood particularly to resuscitate animals 

 that had bled to death. The physicist, Boyle, as well as the anatomist, Lower, 

 took an especially active part in these experiments. The blood of the same or 

 of another species was used. The first transfusion in man was practised by Jean 

 Denis in Paris in 1667 with lamb's blood. 



(a) The erythrocytes are the most important constituents to which the re- 

 suscitating power of the blood is due. They retain their functions even after the 

 blood has been defibrinated. The changes in the red blood-cells produced by 

 time and by prolonged exposure to high temperatures have been described on 

 p. 36. 



(6) With respect to the gases contained in the blood, it is to be remembered 

 that oxygenated blood under no circumstance is injurious. Venous blood can, 

 however, be infused into the blood-vessels of a living being without injury, provided 

 the respiration is sufficient to arterialize the infused blood in its passage through 

 the pulmonary capillaries. Under such circumstances the carbon dioxid contained 

 in the blood is replaced by oxygen in the process of respiration. If the respiration, 

 however, is arrested or if it is not carried on with sufficient activity, the blood, 

 still rich in carbon dioxid, will be conveyed to the left heart and on through the 

 arteries of the medulla oblongata. In consequence there results violent irritation 

 of the centers in that region, followed later by paralysis and even by death. 



(c) The fibrin or the substances forming it take no part in the resuscitating 

 activity of the blood. Therefore, defibrinated blood is capable within the body 

 of assuming with equal success all of the functions that belong to non-defibrinated 

 blood, 



(d) Investigations, especially by Worm-Muller, have shown that the vascular 

 system (dog) is capable of taking up an excess of foreign blood up to 83 per cent., 



