210 PHYSIOLOGY. 



very slowly into a vein (usually the median basilic) in the direction 

 of the heart. Besides giving a tendency toward intra vascular coagu- 

 lation, there is also danger of introduction of bacteria, whose 

 entrance into the injected blood occurs with the beating in the 

 process of defibrination. 



It has been learned that the most serious symptoms of rapid 

 haemorrhage follow the sudden diminution in the amount of blood 

 in circulation, accompanied with a moderate fall of Mood-pressure. 

 From these data we conclude that the proper measures to take are 

 to replenish the amount of fluid regardless of the corpuscles or the 

 soluble nutrient elements of the plasma. A precaution to be taken 

 is that the fluid should be of such a density and n,ature that no dis- 

 turbance in the vascular system be generated. 



This knowledge has led to the manufacture of various artificial 

 solutions for infusion, the one most used being a warm, sterilized, 

 physiological salt-solution (NaCl, 0.75 per cent.) ; this is injected 

 either subcutaneously or into any exposed vein. 



Transfusion is called for after copious hemorrhage (acute anae- 

 mia), or in cases of poisoning when the blood-corpuscles are no 

 longer capable of supplying the tissues with their required supply 

 of oxygen. This condition is particularly prominent in carbon- 

 monoxide (CO) poisoning. 



Plethora. The old physicians admitted that there was in cer- 

 tain individuals of sanguine temperament an exaggerated richness 

 of the mass of blood as a consequence of too active nutrition. How- 

 ever, it is impossible to. verify in an experimental manner if the 

 mass of blood be augmented. Yet plethora is usually accompanied 

 with a swelling of the veins and arteries; an injection of mucous 

 membrane ; a full, hard pulse ; congestive vertigo, and dyspnrea from 

 pulmonary congestion. Many physicians believe that there is no 

 such condition as too much blood in the body, unless it be intro- 

 duced experimentally by transfusion. The above symptoms are 

 explained by reason of an increased peripheral circulation at the 

 expense of the more central one. Nevertheless, the above-named 

 symptoms disappear by blood-letting, which would seem to admit the 

 existence of plethora to a certain extent. 



An experimental plethora may be induced in dogs by trans- 

 fusion; so that the blood may be increased from 80 to 100 per cent, 

 without provoking any trouble. The injected plasma is soon gotten 

 rid of, but the surplus corpuscles remain for a long time. There 

 is also believed to be an increase in the number of red corpuscles in 



