SALIVARY GLANDS, STOMACH AND INTESTINES 737 



glucose in vitro, and that, in vivo, such extracts to some extent inhibit 

 morphin, phloridzin and adrenalin glycosuria. He suggests a possible 

 functional relationship between the salivary glands and the pancreas. 



Stomach. Early Work with Gastrin. In 1906 Edkins demonstrated 

 in an anesthetized cat that the intraveneous injection of a 0.4 per cent 

 hydrochloric acid extract of cardiac or pyloric gastric mucous membrane, 

 causes a secretion of gastric juice, but that similarly prepared extracts 

 from the fundus region do not possess this activity. The method he em- 

 ployed was that of washing out the stomach with water before and after 

 the injection, and in case increased acidity was observed in the second 

 washing, it was considered as proof of secretory activity as a result of 

 the injection. This method is open to many objections, in that the anes- 

 thetized stomach is not a reliable criterion ; also, in that the introduction 

 of water alone may itself act as a stimulant to gastric secretion, and 

 further, in that the intravenous injection causes only a slight and transient 

 response in the gastric mechanism. Edkins interpreted his results as 

 showing that a gastric secretin, gastrin, is elaborated in the pyloric region 

 specifically. About the same time that Edkins made these observations, 

 Gross (1906), independently, in Pawlow's laboratory, also came to similar 

 conclusions. He found that the introduction of beef extract into the 

 pyloric part of the stomach caused a flow of gastric juice, whereas if placed 

 in the fundal part no such response was observed. Both of these ob- 

 servations suggest a specific endocrine secretagogue function on the part 

 of certain areas in the gastric mucous membrane. A careful review of 

 the literature will, however, show that this is by no means definitely 

 established. 



Let us examine the experimental evidence as to the specific formation 

 or distribution of gastrin, the specificity of its physiological action and 

 the specific chemical nature as far as it is known. 



The Specific Formation or Distribution of Gastrin Activity. As 

 early as 1906 Popielski attacked the entire secretin theory, and since then 

 has repeatedly contended that the experimental observations do not uphold 

 the validity of such a theory. His work will be referred to again under 

 the discussion on the intestine, but at this point it is desirable to call 

 attention to his most sweeping and general conclusions. He considers a 

 substance, "vasodilatin," not yet purified, to be very generally distributed 

 in tissue extracts ; and that this substance when injected causes any or all 

 of the following physiological reactions general excitability, convulsions, 

 vomiting, defecation, urination, salivation, stimulation of gastric, pan- 

 creatic and intestinal secretions, an increased flow of bile, a fall in blood 

 pressure and a decreased coagulability of the blood. It is clear that 

 Popielski does not believe in any of the specific endocrine functions of the 

 digestive glands, as they are usually considered at present, but rather 

 that a certain physiologically active substance, "vasodilatin," is very 



