70 THE INVOL UNTAR Y NER VO US S YSTEM 



at the attachment of the prepuce and is continued backwards in 

 the middle line over the ventral surface of the corpus spongiosum 

 and bulbus urethrae. Langley and Anderson have shown that 

 stimulation of the pelvic nerve causes relaxation of this muscle, 

 while, since it belongs to the dermal system, its motor cells are 

 situated in the lateral chain of ganglia of the sympathetic system, 

 the particular ganglia involved being, according to Langley, in 

 the cat and dog the three sacral ganglia : the motor fibres from 

 these ganglia reach the muscle by way of the pudic nerve. The 

 cells on the pelvic nerve, with which the inhibitory fibres are 

 connected, are situated in the neighbourhood of the retractor 

 muscle itself. 



In precisely the same manner the unstriped musculature 

 around the anus and in the perineal region, which also belongs to 

 the dermal system and receives motor fibres from cells in the 

 lateral chain, according to Langley and Anderson relaxes on 

 stimulation of the pelvic nerve ; these inhibitory cells again are 

 situated in the neighbourhood of the muscles. We see then 

 that, as far as these few muscles of the dermal system are con- 

 cerned, their inhibitory cells have not travelled out in the same 

 outflow as their motor cells, but in the same outflow as the 

 motor cells of the endodermal musculature of the cloaca. 



In the case of the rest of the dermal system, namely the 

 whole pilo-motor group, the musculature of the sweat glands, 

 etc., we have at present no knowledge of any inhibitory fibres 

 at all. 



The next group for consideration is the genitodermal group 

 of muscles, the motor nerve cells of which have travelled out in 

 connexion with the thoracico-lumbar outflow, and are situated 

 almost all, if not all, in the neighbourhood of the musculature 

 itself. The evidence for the existence of inhibitory nerves to this 

 system is based largely on the action of adrenalin, after ergo- 

 toxin has been given. 



Dale has obtained from ergot a substance to which he has 

 given the name ergotoxin, which possesses the remarkable pro- 

 perty of paralyzing only the motor nerves of the sympathetic 

 system ; so that in the case of a particular muscle group, which 

 is supplied with motor and inhibitory fibres by a combined sym- 

 pathetic nerve, and in which stimulation or the application of 

 adrenalin normally gives only motor effects, after the injection of 



