THE NERVOUS SYSTEM. 89 



also been many cases of children born almost wholly without 

 nervous matter, above the medulla oblongata, which yet have lived 

 and grown for days, or even for several months. 



The parts above the medulla oblongata, viz., the cerebrum and 

 Cerebellum, are generally considered as the especial seat of intellect 

 and moral feeling. Says Haller, " Concerning the seat of the soul, 

 we must inquire experimentally. In the first place, it must be in the 

 head, and not in the spinal marrow. For though the latter be 

 affected, the integrity of the mind remains the same. Again, it 

 appears, from the experiment of convulsions arising when the in- 

 most parts of the brain are irritated, that it lies not in the cortex, 

 but in the medulla ; and not improbably, in the crura of the 

 medulla, the corpora striata, thalami, pons, medulla oblongata, and 

 cerebellum. Finally, by another not absurd conjecture, it lies 

 at the origin of every nerve, so that the concurrence of the first 

 origins of all the nerves, make up the sensorium commune. Are 

 the sensations of the mind represented there, and do the voluntary 

 and necessary motions arise in that place 1 This seems very pro- 

 bable. For it does not seem possible, that the origin of motion can 

 lie below that of the nerve ; for that would be a gratuitous suppo- 

 sition of immobility or insensibility, In some part of the nerve, 

 though perfectly similar to the rest. Nor can the origin of motion 

 be placed higher in the arteries, for they neither have feeling, nor 

 are excited to voluntary motion. It therefore follows, that the seat 

 of the mind must be where the nerves first begin. 



We come now to the explanation of the manner in which the 

 nerves are the organs of the sense or motion ; which, as it lies 

 hid in the ultimate elementary fabric of the medullary fibres, seems 

 to be placed above the reach both of our senses and reason ; but 

 we shall endeavor to make as great an approximation to the truth 

 as possible, by experiments. First, it is demonstrated, that sensa- 

 tion does not come through the membranes from the sentient 

 organ to the brain, and that motion is not transmitted through the 

 coverings from the brain into the muscle. For the brain itself, 

 deeper than these membranes, receives the impressions of sense, 

 and when injured throws the muscles into convulsions. Moreover, 

 it is certain, that the nerves arise from the medulla of the brain ; 

 the truth of which is manifest in all the nerves of the brain, more 

 especially in the olfactory, optic, fourth and seventh pair, which 

 continue their medullary fabric a long way before they receive the 

 covering of the pia mater." 



