071 the Beflex Function of the Spinal Marram, 127 



urinarise. These muscles cannot themselves be excited to con- 

 tract by the stimulus of the excrement and urine, but these 

 substances act on the sensitive nerves of the mucous mem- 

 brane, and excite the spinal marrow, which, constantly charged 

 with motor nervous power, acts back on these muscles ; there- 

 fore after injury of the spinal marrow the contraction of these 

 muscles ceases. 



"2. The second case is, where the sensorial excitement 

 being quite local, the reflex acting excitement from the brain 

 is more diffused, as shown already in the phsRUomena which 

 accompany cough, in which not only the nervi vagi, but the 

 spinal nerves supplying the thoracic and abdominal muscles, 

 act in coincidence. It is the same with a number of spasmo- 

 dic respiratory motions, sneezing, hiccup, vomiting, &c., all of 

 which are produced by stimuli of the sensitive nerves of the 

 system of mucous membranes of the respiratory organs and 

 intestinal canal, which stimuli are reflected to the brain, and 

 thence put in action the source of the respiratory motions in 

 the medulla oblongata. I have already in p. 333* mentioned 

 the remarkable peculiarity, that the system* of respiratory 

 nerves may be put in action by local stimuli applied to all 

 mucous membranes. For all the motions, cough, sneezing, vo- 

 miting, spasmodic involuntary discharge of faeces, involuntary 

 forcible passage of urine, arise from violent irritation of the 

 mucous memljranes of the fauces, oesophagus, stomach, in- 

 testines, and respiratory apparatus. Sneezing has been ex- 

 plained as a spasmodic affection of the diaphragm; Tiedemannf 

 and Arnold J still speak thus of it: however, it has probably 

 nothing to do with the diaphragm, for it is a violent expiration, 

 and the diaphragm is no expiratory muscle, but the contrary. 

 Under the incorrect supposition that sneezing resulted from 

 the diaphragm, the stimulus of the nasal nerves was consi- 

 dered to be propagated to the spheno-palatine ganglion, the 

 Vidian nerve, the sympathetic, the cervical nerves, the phre- 

 nic, the accessorius Willisii, and the facial §. The highly 

 talented Tiedemann endeavours also to prove that sneezing 

 does not result from a reflected stimulus from the brain, and 

 supports himself on the fact, that a man has still sneezed 

 from snuff, without any sense of smell. Why should he not, 

 seeing that when the nerves of smell are deficient, the nerves 

 of common sensation in the nose, the nasal nerves, have still 

 as in healthy men the perception of tickling? But by minute 

 anatomy the explanation of a sympathy can still only be 



♦ See note p. 53. t Zeitschrifi, i. 278. 



J Der Kopftheil det Vegetal, Nervensystem, p. 181, 

 i Tiedemann, I. c, p. 278. 



