RESEARCHES ON CHLOROFORM ANAESTHESIA 627 



the tissue elements, or cells of the bod}', are poisoned in different 

 degrees, and the cells of the central nervous system in higher 

 animals exhibit a peculiar elective or selective power in picking 

 up such a drug as chloroform, compared with other portions 

 of the excitable tissues or neuro-muscular apparatus of the 

 body. No matter by what particular h3'pothesis this selective 

 power is explained, it is equally certain that chloroform does 

 not actually accumulate in the tissues, or remain permanently 

 held by protoplasm, for a restitution of the normal functions 

 of the whole body is always to be seen, provided that the 

 interference with function has not been of too long a duration. 

 As an explanation of the anaesthetic state some observers 

 on insufficient grounds have attributed this to a local anaemia of 

 the cerebral cortex. But it is known that this view is not in 

 accord with experimental evidence, for the opposite occurs in the 

 early stages of chloroform narcosis ; and as Roy and Sherrington 

 and also Hiirthle have demonstrated, the blood-flow through 

 the brain is actually increased. In profound anaesthesia, the 

 bulbar centres — those complex nerve-cell aggregations which 

 physiologists speak of as the vaso-motor centres, which control 

 the bore of the smallest arteries, so that these are in no sense 

 inert tubes of constant diameter, the respiratory centres con- 

 trolling the muscular movements of the thorax, and the cardiac 

 nerve-centres, which govern the liberation of energy by the 

 heart muscle — become paralysed. Frequently these centres are 

 finally poisoned in the order in which they have just been 

 mentioned, and then, owing to a vaso-motor paralysis, which is 

 particularly a feature of chloroform poisoning, such a quantity 

 of blood may accumulate in the dilated blood-vessels that a true 

 cerebral anaemia may occur. Here it may be mentioned that 

 experiments upon animals have yielded incontestable evidence 

 that among mammals the vaso-motor nervous mechanism is 

 more perfectly developed in a physiological sense in man than 

 in the apes, in the apes than in the carnivora, in these more 

 than in rodents. As Leonard HilP has shown, the explanation 

 of this perfected mechanism in man is related to his erect 

 posture, and the circulation of blood through the brain is 

 maintained at a normal value, whether an animal is placed 

 in a horizontal position or in the feet-down or head-down 

 position. 



' Journal of Physiology^ vol. xviii. 1895. 



