The Mid- Winter Meetings. 187 



On the Alleged Adaptation of the Salivary Glands to Diet. By F. P. Underhill 



, and L. B. Mendel. 



The experiments reported corroborate the current statement that the saliva of 

 dogs and cats is devoid of amylolytic properties. Neilson and Terry {American 

 Journal of Physiology, vol. 15, 1906, p. 406) have announced that dog's saliva 

 frequently will digest starch; and they claim to have increased the amylolytic 

 power by appropriate (carbohydrate) feeding. An inspection of their data, how- 

 ever, indicates that the amylolytic activity is not very pronounced when compared 

 with that ordinarily observed in human saliva. We have failed to note similar 

 results in ordinary dogs and to obtain adaptation in animals maintained on a special 

 diet rich in starchy foods. Special attention was devoted to the conditions under 

 which the digestion trials were conducted. 



After the presentation of this paper Dr. Neilson stated that he had additional 

 evidence obtained since the publication of his paper with Dr. Terry, of adaptation 

 of the salivary glands in man as well as in dog. 



Some Observations on the Oesophagus after Bilateral Vagotomy. By W. B. Can- 

 non. 



On the Mechanism of the Refractory Period in the Heart. By A. J. Carlson, 



University of Chicago. 



One series of the experiments was directed toward determining whether the 

 refractory state of the heart is a property of the heart muscles or the nervous tis- 

 sue or both. The other series aimed to determine the degree of refractory state 

 exhibited by the different parts of the vertebrate heart. If there is a causal con- 

 nection between automatism and a refractory state in the sense of an absolute 

 inexcitability, we ought to find this condition in the primum movens of the heart, 

 the sinus, or in mammals, the mouth of the great veins; and we would expect a less 

 degree of refractory state or even none at all in parts of the heart not automatic, 

 for example, the tortoise ventricle or the apex of the frog ventricle. 



1. The Tissues of the Heart Concerned in the Property of the Refractory State. 

 I. The automatic heart ganglion of Limulus exhibits the typical refractory period 

 of the heart or a state of reduced excitability during systole. 



2. As long as the heart ganglion is in physiological connection with the heart 

 muscle, the heart muscle and nerve plexus exhibit a condition of reduced excit- 

 ability at the beginning of systole. This result is obtained from all regions of the 

 heart. A stimulus strong enough to produce an extra beat by acting on the heart 

 muscle and nerve plexus fails to produce any visible effect when sent through the 

 same tissues, at the beginning of the normal systole. 



3. Do the Limulus heart muscle and motor nerve plexus exhibit a systolic 

 refractory state after being severed from the ganglion .'' The results of the experi- 

 ments were not conclusive, mainly because of the difficulty of getting a series of 

 contractions of absolutely uniform amplitude from the Limulus heart after the nerve 

 cord is removed. 



4. Is the refractory state in the vertebrate heart a property of the heart muscle 

 apart from the intrinsic heart ganglia and nerve plexus.? (i) It is needless to 

 say that this question has not so far, and perhaps never can be, attacked by direct 

 experiments. Rohde and Schultz have attempted to settle this question by 

 studying the action of chloral hydrate on the heart. But in chloral hydrate nar- 



