WORK UPON VISCERAL AND ALLIED NERVES. 35 



cord caused erection of hairs in the tail, but that this effect 

 disappeared after section of both lumbar sympathetic cords. 

 Independently of this, and of one another, Langley ^ dis- 

 covered that stimulation of the lumbar sympathetic in the 

 cat caused erection of hairs, and Sherrington that stimula- 

 tion of the cervical sympathetic in the monkey produced a 

 similar effect. Starting with this as a basis Langley ^ has 

 thoroughly worked out the course and distribution of these 

 fibres, employing his results as a general indication of the 

 arrangement of fibres of the sympathetic system. 



He has shown that in the cat they arise from the cord 

 in the anterior roots from the fourth thoracic to the third 

 lumbar inclusive. In rare cases some were also found in 

 the third thoracic and at times in the fourth lumbar, but, 

 probably, only in the latter nerve, in those cats in which the 

 arrangement of the lumbo-sacral plexus is posterior. These 

 fibres leave the mixed nerve in its white ramus communicans 

 and run to the corresponding ganglion, thus entering the 

 sympathetic system. From these ganglia they may run 

 upwards or downwards and ultimately leave in the grey 

 rami to the various nerves and so reach the skin areas 

 which they supply. 



In a typical nerve all the pilo-motor fibres joining by 

 its grey ramus pass into the posterior primary division of 

 the nerve and are thus distributed to serial areas of the skin 

 of the back which do not to any extent overlap one another. 



This course was further examined to determine whether 

 any nerve cells were interpolated on it. The method 

 employed was that previously described by . Langley and 

 Dickinson,^ who found that a solution of nicotine exerted 

 a specific paralysing action on ganglion cells whether 

 injected into the animal or applied locally, in i per cent, 

 solutions, to the ganglion. After painting a ganglion with 

 this solution he found that stimulation of the pilo-motor 

 fibres running to this ganglion to leave it by its grey 



^ Jonrn. of Physiol., vol. xii., p. 278, 189 1. 

 '^ Ibid.., vol. XV., p. 176, 1894. 



^ Proc. Roy. Soc, vol. xlvi., p. 423, 1889, and vol. xlvii., p. 379, 

 1889-90 ; Joiirn. Physiol.., vol. xi., p. 265, 1890. 



