230 ANIMAL FORCES. [ii. 



of the body, a certain external impression is not reflected in 

 its course to the brain, or changed into a non-conceptional 

 impression, and in which direct actions result, but not those 

 indirect actions as would have occurred had not the reflexion 

 been prevented (425, ii). There are numerous instances of 

 this kind, in which the impression is naturally not felt, and 

 not transmitted to the brain, and which render it probable that 

 there are secondary points in the nerves, whence it must be 

 reflected, and sent in a certain direction, where it is to be 

 changed into a non-conceptional internal impression. A great 

 number of external sensations, and also of unfelt external im- 

 pressions on the stomach and intestinal canal, are never com- 

 municated to the muscles of the limbs, although these two 

 kinds of nerves are in close connection : there are also impres- 

 sions of this kind, which are not felt (48), yet excite the most 

 violent convulsions. Here we can only say, with reference to 

 the greater number of these impressions on the nerves of the 

 stomach and intestinal canal, that the points where the latter 

 come into contact with the nerves of the muscles, are not duly 

 excited, or do not reflect the external impression. Since many 

 of these impressions are, in fact, felt, it is certain that they 

 reach- the brain, and if they had been reflected, they would 

 also have excited the muscles to action; unless it be that the 

 impressions actually reflected do not reach the muscles, being 

 interrupted (as shown in the next section) in their course be- 

 tween the point of reflexion and the mechanical machines. 

 In the examples above quoted, this is neither demonstrable 

 nor probable. 



429, vii. Wlien an external impression on its way to the 

 brain is actually reflected and transformed into a non-concep- 

 tional internal impression, but is not transmitted back again 

 along the nerve which received it, or on account of a natural 

 deflection by means of intervening ganglia, or plexuses, or is 

 reflected upon a certain other nerve, the nerve-actions which 

 usually result from it, do not take place, but those mechanical 

 machines are put into motion in connection with the nerve 

 along which the impression is deflected (425, iii). This case 

 often occurs naturally (137), but the proof is difficult. When 

 an external impression has caused an external sensation, we 

 know that it has reached the brain, and that the cerebral 



