WORK UPON VISCERAL AND ALLIED NERVES. 49 



opposite vagus was cut. Doyon ^ confirms this result and 

 adduces further evidence of the presence of these inhibitory 

 fibres in the vagus, for he finds that after the injection of 

 pilocarpine the first effect of stimulation of the vagus is to 

 produce dilatation which is later followed by the usual 

 contraction. The injection of strychnine in suitable doses 

 gives practically the same result. 



Contejean - experimenting on frogs and toads describes 

 the vagus as carrying motor fibres to the general stomach 

 wall and to the cardiac and pyloric sphincters, and in addi- 

 tion fibres inhibiting movements of the sphincters. By a 

 weak stimulation inhibitory effects are produced; with strong 

 stimulation energetic contraction of the cardia and pylorus, 

 then of the longitudinal fibres and finally peristalsis ; stimula- 

 tion of the sympathetic, or better of the coeliac plexus, leads 

 to contraction of the circular fibres, but not peristalsis. If 

 in a curarised frog water be placed in the mouth after both 

 vagi are cut this is not driven into the stomach, and the 

 cardiac orifice shows marked rhythmic contractions, thus 

 illustrating the absence of the usual inhibitory effects. If, 

 on the other hand, both vagi be cut in a non-curarised frog 

 the results obtained are due to a failure of the usual motor 

 effects, e.£:, air taken into the mouth is driven into the 

 stomach as well as into the lungs, 



Doyon ^ has examined the innervation of similar parts 

 in pigeons and fowls. The crop is a part of the oesophagus 

 and is innervated in a similar manner to it. The gizzard 

 and proventriculus show rhythmic contractions which are in- 

 creased in number and in rate by vagal stimulation and also 

 increased in tonus. Stimulation of the splanchnic arrests 

 rhythmic movements if these be present, but if the organs 

 be at rest it may produce a single contraction. Stimulation 

 of the central end of the vagus the other being intact causes 

 relaxation of the gizzard and proventriculus, an effect which 

 is abolished by section of the opposite vagus. Pilocarpine 



^ Arc/i de Physiol., vol. xxvii,, p, 374, 1895, 



'^ Co7np. Re?id., vol. cxiii., p. 150, 1891, and Arch, de Physiol., vol. 

 :xxiv., p. 640, 1892. 



^ Arch, de Physiol., vol. xxvi., p. 887, 1894. 



4 



