in DIGESTION IN THE MOUTH AND STOMACH 189 



then killed at different periods, and the quantity of water left in 

 the stomach was measured. In the first 12 minutes nothing was 

 absorbed or expelled by the pylorus ; after 15 minutes evacuation 

 commenced and was completed after 30 minutes. 



In children the water in the stomach can easily be detected 

 radioscopically. The rapidity of expulsion varies very much ; in 

 some children it begins at once, in others after 13 minutes. In 

 some the horizontal level of the fluid sinks gradually, no waves of 

 muscular contraction being perceptible ; 100-125 c.c. of water 

 required 8-13 minutes for evacuation ; 250 c.c. 19 minutes ; warm 

 water disappears faster than cold ; the presence of solids in the 

 stomach delays evacuation to a remarkable extent. In another 

 group of children muscular contraction obviously co-operates. 

 The time required by the stomach for evacuation varies consider- 

 ably, according to the nature and quantity of the food. Nearly every 

 one, however, agrees that after 5-7 hours the stomach is usually 

 almost empty, unless there has been an excessively abundant meal, 

 as we saw in discussing gastric digestion. 



By some the distension of the stomach walls by the presence 

 of food is held to be a mechanical stimulus to the excitation of 

 gastric movements. Spallanzani first pointed this out in birds. 

 A guinea-fowl that had fasted for a day was made to swallow 

 hazel-nuts, and its stomach watched through an aperture made in 

 the abdomen. "As long as the stomach contained only a few 

 nuts, no movement was visible, but as it became filled I saw it 

 swell out, and suddenly get flat again," i.e. it exhibited systoles 

 and diastoles similar to those observed in the dog's pyloric 

 antrum. 



Schiitz observed regular peristaltic movements in a dog's 

 stomach, isolated from the body, after insufflations of air through 

 a cannula tied in the oesophagus. This is a reflex phenomenon, 

 discharged by the mechanical stimulus, and effected by the ganglion 

 plexus situated in the stomach. 



Many authors have verified Magendie's discovery that a solid 

 body introduced into the pyloric antrum is at once shot out, and 

 falls into the fundus. This proves the excitability of the stomach 

 to mechanical stimuli, under conditions not far removed from the 

 physiological. 



Some interesting details can be deduced from the work of 

 Ducceschi. Twenty-four hours after a meal the stomach is 

 immobile, its movements commencing immediately after food. 

 Introduction of an exploring balloon into the empty stomach, 

 however, at once excites the movements. In proportion as the 

 distension of the balloon increases by the introduction of a 

 constantly increasing amount of water, the gastric movements 

 become more ample while their rhythm is approximately constant. 

 There is, however, a limit to the distension of the stomach, 



