PHYSIOLOGY CHAP. 



have a short latent period, the augmentor fibres a long latent 

 period. The action of the vagus on the intestines is therefore 

 twofold an initial inhibition, followed by augmentation which 

 mitlasts the excitation of the nerve. 



Little is accurately known as to the localisation of the cerebro- 

 spinal centres of the nerves which influence the intestinal move- 

 ments. It is supposed that the spinal centres for the splanchnics 

 lie in the lower part of the cervical cord and the upper part of 

 the dorsal cord. But according to Ott inhibitory effects are also 

 obtained with stimulation of the optic thalami and the cerebral 

 peduncles. According to Budge and Valentin the intestinal 

 movements can also be excited by electrical stimulation of the 

 corpora quadrigemina and corpora striata ; according to Schiff, also 

 by that of the medulla oblongata, the annular protuberance, the 

 cerebral and cerebellar peduncles. Bochefontaiue in Vulpian's 

 laboratory obtained movements of the intestines from dogs, with 

 faradic stimulation of certain points of the motor zone of the 

 cerebral cortex. 



Bechterew and Mislawsky, and Bunch, tried to ascertain which 

 roots of the spinal nerves give off fibres to the intestines, by way 

 of the sympathetic cord. According to Bunch the fibres that run 

 to the splanchnics originate in the anterior roots of the sixth 

 thoracic and succeeding pairs of nerves, down to the second, 

 third, fourth, and fifth lumbar pair. On their way to the small 

 intestine they traverse the ramifications of the solar plexus, in the 

 ganglia of which they have a cell station. 



The above discussion shows that the physiological theory of the 

 nerve centres and the central and peripheral, afferent or efferent, 

 nerve paths which regulate the intestinal movements, is still very 

 incomplete, doubtful in places, and fragmentary throughout. 



VIII. Having reviewed the chemical phenomena of digestion 

 carried on in the stomach and intestines, we may opportunely 

 consider the physiological question proposed as early as 1772 by 

 Hunter, which has given much food for thought and experiment to 

 physiologists. 



Hunter was the first who discovered, by dissection of a number 

 of subjects, the phenomenon of the softening of the wall of the 

 gastric fuudus, which may lead to perforation, and the evacuation 

 of the contents of the stomach into the peritoneal cavity. He 

 noted particularly that this condition appeared most frequently, 

 not in persons who had died from disease, but in those who had 

 previously been healthy, and had come to a sudden death. 

 Having confirmed the fact for certain animals some time after 

 they had been killed, he interpreted it as a result of the digestion 

 effected by the gastric juice, which continued after death, and 

 dissolved not only the food-stuffs ingested, but the stomach 

 itself, after it had been deprived of the " vital principle." He 



