WITH THE MICROSCOPE. 129 



textures. He will find the process, detailed in part V, of great value 

 in such enquiries. 



b. Pale Grey or Sympathetic Nerve Fibres. Some observers still 

 support the assertion that every true nerve is characterised by being 

 dark bordered, exhibiting the double contour lines caused by the 

 investment of the medullary sheath, the so-called white substance of 

 Schwann. Remak, however, correctly described, nearly thirty years 

 ago, the pale grey or gelatinous nerve fibres of the sympathetic 

 system, but his views were strongly opposed by a majority, and his 

 nerve fibres were authoritatively pronounced to be mere connective 

 tissue. They have since been named ironically RemaK s fibres . In 

 Germany, for years past, many anatomists have been trying to reduce 

 everything to what they call connective tissue, which to any ordi- 

 nary observer would appear to be the least important tissue in the 

 organism. It is even now a matter of the utmost difficulty to get a 

 fair hearing if you attempt to extract anything real and definite out of 

 this favoured indefinite connective tissue. In spite of all this, how- 

 ever, it has been clearly proved that Remak's fibres are true nerve 

 fibres, and that dark-bordered nerve fibres before they reach their 

 ultimate distribution, invariably assume the pale granular appearance 

 of Remak's fibres. So far from the dark-bordered character being 

 essential to nervous structure, the active peripheral portion, the really 

 important part of every nerve fibre, never exhibits it. The white 

 substance after all appears to be merely a passive fatty albuminous 

 matter which surrounds the conducting core of the nerve fibre and 

 insulates it from neighbouring fibres. It is peculiar to the trunks 

 of nerves which connect the great central organs with the distant 

 peripheral ramifications. 



Into many sympathetic ganglionic nerve centres, however, pale 

 fibres may be traced, and no medullary sheath exists in any part of 

 the course of the nerve fibres. These sympathetic nerves in fact 

 form an extended network or plexus which corresponds to the peri- 

 pheral network of the cerebro-spinal nerves. The distance from their 

 central origin to their peripheral distribution is so short that there is 

 not that need of insulation as in the case of the fibres coming from the 

 brain and spinal cord. Sympathetic nerve fibres and their ganglia are 

 represented in pi. XXXI, figs. 199 to 201, and the mode of connection 

 of the fibre with the ganglion cell is seen in fig. 202. Many observers, 

 however, still maintain that the appearance is due to the ganglion cells 

 being enclosed in a capsule of connective tissue, and assert that some 

 cells exist from which no fibres whatever proceed. These strange 

 notions are still taught in many of our most celebrated text books, and 

 are erroneously forced upon the mind by the repetition of old figures. 



