THE DISCOVERY OP MOTOR AND SENSORY NERVE CHANNELS. 299 



this is only if it be a simple organ of feeling, and is not in its office connected 

 with respiration. 



' From the nerve that comes off from the anterior ganglion of the leech, and 

 which supplies its mouth, we may trace up through the gradations of animals a 

 nerve of taste and manducation until we arrive at the complete distribution of the 

 fifth or trigeminus in man (see Plate XXX., B.C.D., which are its three grand 

 divisions to the face). Here in the highest link, as in the lowest, the nerve is sub- 

 servient to the same functions. It is the nerve of taste, and of the salivary 

 glands, of the muscles of the face and jaws, and of common sensibility. This 

 nerve comes off from the base of the brain in so peculiar a situation that it alone 

 of all the nerves of the head receives roots both from the medullary process of 

 the cerebrum and of the cerebellum. A ganglion is formed upon it near its origin, 

 though some of its filaments pass on without entering into the ganglion. Before 

 passing out of the skull the nerve splits into three great divisions, which are sent 

 to the face, jaws, and tongue. Its branches go minutely into the skin and enter 

 into all the muscles, and they are especially profuse to the muscles wliicJi move 

 the lips vjwn the teeth. 



Revised version. Reprint of 1824, pp. 95-6. 

 Of the Trigeminus or Fifth Pair. 



' In all animals that have a stomach, with palpi or tentacula to embrace their 

 food, the rudiments of this nerve may be perceived; and always in the vermes, 

 that part of their nervous system is most easily discerned which surrounds 

 the oesophagus near the mouth. If a feeler of any kind project from the head of 

 an animal, be it the antenna of the lobster or the trunk of an elephant, it is a 

 branch of this nerve which supplies sensibility. But this is only if it be a 

 simple organ of feeling, and is not in its office connected with respiration. 



' From the nerve that comes off the anterior ganglion of the leech, and which 

 supplies its mouth, we may trace up through the gradations of animals a 

 nerve of taste and manducation until we arrive at the complete distribution of 

 the fifth or trigeminus in man (see Plate III., in which there are its three 

 grand divisions of the' face). Here in the highest link, as in the lowest, the 

 nerve is subservient to the same functions. It is the nerve of taste, and of the 

 salivary glands; of the muscles of the jaws, and of common sensibility. This 

 nerve comes off from the base of the brain in so peculiar a situation that it 

 alone of all the nerves of the head receives roots both from the medullary pro- 

 cess of the cerebrum and of the cerebellum. A ganglion is formed upon it near 

 its origin, though some of its filaments pass on without entering into the 

 ganglion. Before passing out of the skull, the nerve splits into three great divi- 

 sions, which are sent to the face, jaws, and tongue. Its branches go minutely 

 into the skin, and enter into all the muscles, and they are especially profuse to 

 the lips.' 



The differences between the two passages are very small but very 

 important; they are three in number: — 



At line 6 the words ' and animates its muscles ' are deleted. 



At line 15 the words ' face and ' are deleted. 



At the last line ' to the muscles which move the lips upon the 

 teeth ' is replaced by the words ' to the lips.' 



The net result of these three emendations is that the fifth nerve 

 (i.e., its portio major) which is motor and sensory in Bell's original 

 paper of 1821 is sensory only in his republication of 1824. 



In the third edition of Bell's ' Nervous System ' (1836 and 1844) 

 at p. 48 the passage is substantially as in the revised version of 1824, 

 the only difference being that now the words 'from the column of 

 sensibility and from that of motion ' are substituted for the words 

 ' from the medullary process of the cerebrum and cerebellum ' used 

 in the versions of 1821 and of 1824. 



