x] of the Nervous System. 297 



many have thought, aerial. " At the close of the 17th century," 

 he says, " the name ether came into fashion, and it became 

 " the wont to attribute to it, to an invisible element which did 

 " not lend itself to experiment, everything the cause of which 

 " was unknown, light, gravity, magnetism. Some accordingly 

 " hold the spirits (the nervous fluid) to be of the nature of 

 " ether or to be composed of ether." He rejects this also, 

 including in the rejection the view that the spirits consist of 

 electric material. 



'' Of what nature then," he asks, " is the material of these 

 " spirits ? " He answers, with the spirit of the eclectic philo- 

 sopher that he was, " an element of its own kind unlike 

 "everything else. An element, too subtle to be grasped by 

 " any of the senses, but more gross than fire, or ether or 

 " electric or magnetic matter, since it can be contained in 

 " channels and restrained by bonds and moreover is clearly 

 " produced out of and nourished by food. What forbids, since 

 " light is something different from fire, and the material of 

 "the magnet differs from 'both, and air and ether are unlike 

 u all the rest, what forbids that there should be this element of 

 " its own kind known to us only by its effects ? " 



He then discusses as a speculation, but be it observed 

 as a speculation only, whether the nerves are hollow for the 

 conveyance of this nervous fluid ; he decides in the affirmative 

 and insists that by analogy the fibres of the brain must in like 

 manner be hollow also. He adds that the nervous fluid is 

 supplied and nourished by the arteries of the brain. 



He rejects the view of there being two different kinds of 

 nervous fluid, one for the production of sensation and movement, 

 and another for the preservation of life, one connected with the 

 cerebrum, the other with the cerebellum. He rejects also the 

 view that there is one kind of nervous fluid for sensation and 

 another for movement; he sees no real difficulty in the same 

 nerve serving both for sensation and movement. 



Lastly, he passes to the most speculative question of all, 

 the 'seat of the soul.' He rejects the Stahlian opinion that 

 the soul and the sensorium commune is diffused over the 

 whole body, present as well in the tip of the finger as in the 



