ON THE TRANSFUSION OF BLOOD. 691 



other experiment, made in the following way, furnishes a proof of it. 

 Two dogs were submitted to the section of the nervous centre which 

 contains the vital knot, occasioning death. The appearance of death 

 was produced as soon as the starting-point of the respiratory nerves 

 was deeply injured. By slow degrees the nervous tissues lose their 

 properties, and, before they are entirely extinct, the spinal cords of 

 the two animals are exposed. One is subjected to the action of oxy- 

 gen gas, and its sensibility increases ; the other is influenced by hydro- 

 gen gas, and its sensibility remains unchanged. These facts show 

 with absolute certainty that the nervous centres find their conditions 

 of activity in the oxygen of the blood, or, to speak more precisely, the 

 oxygen of the blood-globule. 



The brain, the organ of the highest manifestations of life, performs 

 its action like the spinal cord, and an elaborate net-work of blood- 

 vessels distributes the nutritive fluid throughout all its parts. Yet 

 the mass of the brain does not keep its functional activity constantly 

 at work. The whole organism rests after the day's labor ; the brain, 

 when not waking, preserves only its life of nutrition ; therefore the 

 religions of ancient Greece, not without reason, regarded Sleep as the 

 brother of Death. The quantity of blood transfused into that organ 

 during these two conditions, so different, of sleep and wakefulness, is 

 not the same. Dr. Pierquin had the opportunity of making observa- 

 tions upon a woman in whom disease had destroyed a large part of the 

 bones of the skull, and deprived the brain of its membranous cover- 

 ing ; the nerve-mass, quite exposed, shone with that brilliant lustre 

 observed in all living tissue. While at rest in sleep, the substance of 

 the brain was pink, almost pale ; it was depressed, not protruding 

 beyond its bony case. At once, when all the organs were quiet, the 

 patient uttered a few words in a low voice ; she was dreaming, and in 

 a few seconds the appearance of the brain completely changed ; the 

 nerve-mass was lifted, and prominent externally ; the blood-vessels, 

 grown turgid, were doubled in size ; the whitish tinge no longer pre- 

 vails ; the eye sees an intensely red surface. The tide of blood in- 

 creases or lessens in its flow, according to the vividness of the dream. 

 When the whole organism returns to quiet, the lively colors of the 

 infused blood fade away by degrees, and the former paleness of the 

 organ is observed again. The succession of these phenomena per- 

 mitted the conclusion that increasing action of the cerebral cells 

 attracts a considerable quantity of blood to them. 



The general circulation in the brain is weak during sleep ; in faint- 

 ing it suffers complete suppression, and every one must have noticed 

 the effects that result in this ors;an from the abstraction of blood. The 

 least emotion, the smell of a flower, can bring on impressions that re- 

 act on the heart, and for a moment suspend its movements ; the blood 

 then ceases to stimulate the brain, and paleness of the face indicates 

 the bloodlessness of the deeper parts. The organism no longer puts 



