248 PHYSIOLOGY CHAP. 



relations of these two nerves, by the chain of the sympathetic, 

 the solar plexus, the superior and inferior mesenteric plexus, and 

 the hypogastric plexus, with the various abdominal viscera, more 

 particularly the intestine. 



Division of one or the other of these nerves, or even of both, 

 has at first no appreciable effect on the movements of the intestine ; 

 in a short time, however, a more or less conspicuous and persistent 

 exaggeration and disturbance ensues, owing to congestion of the 

 blood from the paralysis of the vessels. 



Stimulation of the peripheral end of the splanchnic by the 

 experiments of Joh. Mltller, Ludwig, Nasse, and S. Mayer led to 

 no definite results. Pfliiger (1857) first showed that stimulation 

 of these nerves when the intestines were in vigorous motion 

 arrested the movements, in the same \vay as the vagus causes 

 arrest of the heart, i.e. by producing a relaxation. The same 

 effect can be obtained on exciting the spinal cord between the 

 5th and llth dorsal vertebrae. This observation (though it is 

 not always to be seen as clearly as could be desired) has been 

 confirmed by all subsequent workers. The phenomenon, as dis- 

 covered by Pfliiger, has, however, received different interpretations. 

 Schiff and Valentin, who saw that weak currents applied to the 

 splanchnic increased the intestinal movements, attributed the 

 arrest with strong currents to the exhaustion of the nerve. 

 S. Mayer and von Basch ascribed the standstill to ischaemia of 

 the intestinal walls, due to the vaso-constrictor fibres of the 

 splanchnic. Van Braam-Houckgeest, who at first adopted this 

 opinion, abandoned it later, on noting that even weak currents, 

 which fail to excite the vaso-constrictor fibres of the splanchnic, 

 do inhibit the movements of the intestine, contrary to the opinion 

 of Schiff and Valentin. Moreover, if the viscera of a rabbit are 

 exposed to the air till they become congested by vaso-rnotor 

 paralysis, stimulation of the splanchnics has no effect on the 

 blood-vessels, although the intestinal movements are inhibited 

 as in a normal animal. Jacobi stated, in confirmation of Pfliiger's 

 theory, that the inhibitory fibres of the splanchnic have a different 

 course from the vaso-constrictor fibres, and that section of the 

 nerves running from the suprarenals to the solar plexus annuls 

 the inhibitory action of the splanchnics, without interfering with 

 their vaso-constrictor effect. As regards excitation from the 

 spinal cord, Pfliiger's observation is contrary to that of Cl. 

 Bernard^ who found that a transverse section, or the mechanical 

 stimulation (puncture) of the spinal cord above the origin of the 

 splanchnic, is followed by extremely energetic movements of the 

 intestines. 



Ludwig and Kupfer, Schiff, Bechterew and Mislawsky, Bunch, 

 observed a motor effect in the intestines on stimulating the 

 splanchnics. The last observer, in 1898, obtained tracings from 



