538 MECHANISM OF SECRETION OF GASTRIC JUICE. 



efferent impulses, dilator in character, passing along the sympathetic to 

 the mucous membrane. 



That impulses passing along the vagi influence the movement of the 

 stomach, and possibly by that means to some extent the secretion, has 

 been shown by several observers. 



Goltz 1 exposed the stomach and oesophagus of two curarised frogs, 

 and, after suspending them, dropped into their mouths salt solution. One, 

 however, had had the brain and spinal cord destroyed. After a time it 

 was found that in the complete animal the stomach and oesophagus were 

 widely distended, whilst in the pithed frog they were empty. The latter 

 result occurred equally well if the vagi only were cut. Stimulation of 

 the vagi peripherally caused only slight contractions. The explanation 

 given by Goltz of this result is thafr the stomach walls presumably 

 contain a local mechanism which, under the conditions in which the 

 animals were, would have undergone stimulation. The result of this 

 would have been peristaltic contraction, causing the fluid to be passed on 

 into the intestine. But ordinarily this is controlled by efferent impulses 

 passing from higher centres along the vagi. If the controlling influence 

 is destroyed, there results an exaggerated action of these centres. Goltz 

 was disposed to regard this local mechanism as of a ganglionic nature. 



In connection with this question, it may be stated that Openchowski 2 has 

 described the existence of special nerve-plexuses with ganglionic cells, both at 

 the cardia and at the pylorus. He considers that the opening and closing of 

 these passages are to be referred to the direct influence of these ganglia, though 

 these again are under the control of the central nervous system. Openchowski 

 describes a centre for the contraction of the cardia situated in the posterior 

 corpora quadrigemina, and connected with the stomach mainly by the vagi. A 

 centre for the opening of the cardiac orifice lies in the basal ganglia, and 

 communicates with the stomach by means of the vagus. There are also 

 subsidiary centres in the spinal cord influencing dilatation of the cardiac 

 orifice. In the same regions are centres influencing movements of the pylorus 

 and the intermediate walls of the stomach. Openchowski emphasises the 

 antagonism between the movements of the cardia and the pylorus ; such nervous 

 impulses as proceed down the vagus and dilate the cardiac orifice simultaneously 

 close the pylorus. 



As regards the more direct influence of impulses proceeding along 

 the vagi upon secretion in the stomach, for a long time the greatest 

 uncertainty prevailed, and it was held that in general such impulses did 

 not directly affect secretion, but merely indirectly, through promoting 

 movements of the stomach walls. Heidenhain 3 has suggested that, as 

 mechanical irritation produced secretion from the digestive glands in the 

 plant Drosera, so the direct irritation of food in the stomach might 

 stimulate the gastric epithelium. There has existed for a long time, 

 however, indirect evidence of a flow of gastric juice resulting from 

 psychical conditions. Bidder and Schmidt 4 noticed, as early as 1852, that 

 the sight of food in a gastrostomised dog resulted in an abnormal flow of 

 gastric juice. To obviate any possibility of swallowed saliva causing 

 this result, which saliva it was known could be secreted as the con- 



1 " Studien liber die Bewegung von Speiserohre mid Magen d. Frosche," Arch. f. d. 

 ges. Physiol., Bonn, 1872, Bd. vi. 



2 "Ueber die nervosen Vorrichtungen des Magens," Centralbl. f. Physiol., Leipzig u. 

 Wien, 1889, Bd. iii. 



3 Hermann's "Handbuch/' Leipzig, 1881, Bd. v. Th. 1. 



4 " Die Verdauungssafte mid der Stoffwechsel," Leipzig, 1852. 



