38 



Scientific Proceedings (36). 



considered a substance of our food which reduces gastric secretion 

 from the stomach, and more so from the duodenum and the small 

 intestine. Possibly the depressing effect of fat upon gastric 

 secretion, as discovered by Pawlow, resolves itself into the mere 

 effect of its division product, glycerin. 



Aside from glycerin, there are two other kinds of alcohol, 

 namely, amyl and butyl alcohol, that I have observed to have an 

 inhibitory effect upon gastric secretion. 



23 (433) 

 The summation of stimuli. 



By FREDERIC S. LEE and MAX MORSE. 



\Froin the Department of Physiology of Columbia University at the 

 College of Physicians and Surgeons, Nezv York, and 

 from the Harp swell Laboratory^ 

 The phrase, "summation of stimuli," has been employed at 

 times to signify only the phenomenon in which a stimulus of a fixed 

 intensity, which at first is too weak to stimulate living substance, 

 will upon repetition be followed by a response. It is more rational 

 to include within the concept all cases of summation, whether 

 the stimulus is at first below the stimulation threshold or above it. 

 Summation is usually ascribed to an increase in the irritability of 

 the protoplasm, but the conditions responsible for such increase 

 have not been known. Two years ago, the senior author explained 

 the increase in irritability found in the treppe of muscle, by the 

 augmenting action of fatigue substances, notably carbon dioxide 

 and lactic acid. This chemical theory of the treppe is here applied 

 to the explanation of summation in general. The validity of this 

 explanation has been confirmed by a large variety of experiments 

 performed on the muscles of medusae and crustaceans. It has long 

 been known that summation with subminimal stimuli is very readily 

 obtained in these forms. The authors have confirmed this. They 

 have also studied the action on the muscles of carbon dioxide and 

 lactic acid in small quantities. When a stimulus was found that 

 was just too weak to cause contraction, carbon dioxide was admin- 

 istered to the muscle for a period of a few seconds, either in solu- 

 tion or as a gas. The hitherto subminimal stimulus was then 



