viii] in the Eighteenth Century. 217 



the sponges in the tube. Hence he inferred that what he 

 called gastric juice was a mixture consisting of the above 

 proper secretion of the stomach, " thin, colourless and insipid," 

 together with saliva, juice secreted by the glands of the 

 oesophagus, bile and possibly pancreatic juice ; bile seemed 

 to be always present in his specimens of gastric juice and to 

 this he attributed the bitter taste. The activity of this mixed 

 juice was probably due to the constituent supplied by the 

 stomach itself, for when he introduced into birds, such as 

 crows, two pieces of meat fastened on a wire so that the 

 lower one reached the stomach but the upper remained in 

 the oesophagus, the former was much more readily dissolved 

 than the latter; similarly when he introduced a long rod of 

 meat reaching through the oesophagus into the stomach, 

 this was much corroded at the end which reached into the 

 stomach, but very little above. But he did not follow up 

 the investigation into the properties of pure gastric juice, 

 and contented himself with the results obtained from the 

 mixed contents of the stomach. 



He repeatedly tried to obtain evidence of the presence 

 of acids in this mixed gastric juice but failed to obtain 

 anything which could satisfy him. Though he observed that 

 shells and corals were corroded in the stomach of birds, he 

 could not find any clear indication of acidity in the stomach 

 other than that which was due to the tendency of food to turn 

 sour ; and this says he is an abnormal and not a healthy 

 condition. 



" I repeatedly dropped gastric j uice upon salt of tartar per 

 " deliquium, and into the nitrous and marine acids without ever 

 " perceiving any change of colour, any motion or effervescence ; 

 " whence I am obliged to infer that the gastric juice is neither 

 "acid nor alkaline, but neutral." His own gastric juice, 

 obtained as we have seen by vomiting, he also found to be 

 neutral; and he is confirmed in his belief that acidity of the 

 gastric juice is something abnormal by the reflection that 

 regurgitation of sour material from the stomach into the 

 mouth only occurs when digestion has gone wrong; and he 

 quotes his own experience of acid fluid coming up into his 



