PHYSIOLOGICAL EXPERIMENTATION. 183 



his investigations into the fifth and seventh nerves of the head, the 

 present doctrine of the spinal nerves is nowhere explicitly stated. These 

 memoirs can scarcely, indeed, be read in any other sense ; and "A 

 Manual of Anatomy," published by Mr. John Shaw (another brother- 

 in-law) in 1821, contains a tolerably clear intimation of it. Moreover, 

 Mr. J. Shaw, having visited Paris in 1821, and having repeated to 

 Magendie the experiments on the fifth and seventh nerves which he 

 had made with Sir C. Bell, further pointed out to him (as appears 

 from Magendie's own narration) * the analogy of the fifth to the spinal 

 nerves, and attributed to the double roots of these " regular " nerves 

 this double function of motion and sensation. 



It was at this point that Magendie took up the experimental in- 

 quiry, both as to the roots of the spinal nerves and the functions of 

 the fifth and seventh nerves of the head ; and it will be convenient to 

 dispose of the latter in the first instance. He showed that the second 

 of the three divisions of the fifth pair is a nerve of sensation only ; so 

 that the part of the face which it supplies (between the eyes and the 

 upper lip) depends for its motor action on the seventh pair, which he 

 regarded as the ordinary motor nerve of the face, ministering to its 

 voluntary movements, as well as to those of expression and respira- 

 tion. These corrections (which were confirmed by other experimenters) 

 were not only accepted by Sir C. Bell, but were appropriated by him 

 as his oicn ; the reprints of the two memoirs just referred to being 

 altered in successive editions of his " Nervous System of the Human 

 Body," by omission, addition, and variation, not only without any 

 acknowledgment of the source of the correction, but without the least 

 intimation of a change. It is clear, therefore, that although he shrank 

 from making experiments himself, he was ready enough to profit by 

 those of others. 



On testing experimentally Bell's idea of the functions of the an- 

 terior and posterior roots of the spinal nerves, and varying his experi- 

 ments in every way he could think of, Magendie was only able to 

 arrive at this general conclusion that the anterior roots are more 

 especially motor , and the posterior more especially sensory. For he 

 could not get over the fact that irritation of the anterior roots in the 

 living animal called forth signs of pain, and that irritation of the 

 posterior roots called forth movements. The repetition of the same 

 experiments by others gave no more conclusive results ; until, in 1831, 

 Johann Miiller (afterward the celebrated Berlin professor) was able, 

 by a very carefully devised method of experimentation upon frogs, to 

 show that, for these animals at least, Bell's doctrine was correct. And 

 it was by the extension of the same method to warm-blooded animals, 

 and by the light of the new ideas then dawning f as to the " reflex 



* "Journal de Physiologie," October, 1821. 



f The very clear ideas long before promulgated by Prochaska on this point had been 

 entirely forgotten. > 



