Walter Holbrook Gaskell. 



xxxi 



held by some anatomists that the white rami communicantes constituted the 

 sole connection between the spinal cord and the sympathetic, and brought 

 all the involuntary nerves of whatever origin into one system of ganglionated 

 nerves as had been recently advocated by Dastre and Morat. 



In these conclusions there was one weak spot. Whilst it was definitely 

 shown that the outflow of visceral fibres from the central nervous system 

 to the sympathetic was enormously greater in the regions in which 

 there were only white rami, it was not shown that no fibres passed 

 out by the grey rami. Gaskell's observation of the rarity of small 

 medullated fibres in the grey rami was not in accord with earlier obser- 

 vations, and he did in fact under-estimate their number. Further, physio- 

 logists of repute had described vaso-motor, pupil or heart effects as 

 being caused by stimulation of the cervical nerves, which had grey rami 

 only. It might then be said that the few small medullated fibres present 

 in the centrally running branch of the grey rami represented the few 

 scattered small medullated fibres of the anterior roots of the corresponding 

 spinal nerves. Thus the difference between the thoracic and other regions 

 of the spinal cord might be one of degree only. So far, however, as sub- 

 sequent investigation has gone, Gaskell's conclusion was correct, and the grey 

 rami receive no efferent fibres from the spinal cord. Gaskell's work clarified 

 the air. It gave anatomists and physiologists a clearer view of the general 

 arrangement of the efferent nerves governing unstriated muscle and glands, 

 and it directed the attention of physiologists to points which they had 

 singularly neglected. It is to be noticed also that Gaskell's earlier theory 

 that the heart-beat is not due to the activity of local nerve cells has an 

 intimate bearing on the much discussed question of the automatic and reflex 

 action of peripheral ganglia. 



In the paper setting forth the conclusions given above, Gaskell discussed a 

 number of other problems of the sympathetic system. His theories were based 

 on facts known at the time, but the experiments to test their wider applica- 

 tion were few. Some are still under discussion, some are superseded. The 

 most far-reaching of these theories was on the nature of the difference between 

 motor and inhibitory nerve fibres. In 1881 he had advocated the view that 

 the vagus is the trophic nerve of the heart. Lowit, in 1882, had suggested, 

 on the lines of Hering's theory of assimilatory and dissimilary processes in 

 the body, that the cardiac inhibitory fibres favour assimilation, and that the 

 accelerator fibres favour dissimilation. Gaskell, developing his trophic 

 theory, took a more definite and a wider view and urged that all inhibitory 

 fibres are anabolic, and all motor fibres are katabolic. 



Gaskell's microscopical and anatomical observations led him to questions of 

 morphology. He argued that in a typical spinal segment a lateral root was 

 to be distinguished in addition to the ventral and dorsal roots. The lateral 

 root consisted of two parts, one arose from the lateral mesoblast plates of 

 van Wijhe and supplied the respiratory muscles of Oh. Bell's system, the 

 other formed the ganglionated nerves of the visceral system. On this basis 



