312 RESEARCH SEMINAR. 



attention was first called to the matter by the Weber brothers in 

 1846. A similar relation of the nervous system and heart has 

 been shown to hold among the invertebrates also, notably through 

 the work of Conant and Clark on arthropods, of Ransom, Straub, 

 and Yung on mollusca. The last-named worker has described 

 inhibition of the heart of lamellibranchs on stimulation of the 

 visceral ganglion, but no graphic records have been published 

 illustrating experimental investigations of this kind. 



In this seminar experimental work on the heart of l^enns mer- 

 ccnaria was described, and kymograph tracings exhibited, which 

 seem to warrant the following conclusions : 



1. Normal rate and character of the heart-beat varies widely 

 with different individuals. 



2. Partially exhausted hearts show extreme irregularities. 



3. Electrical stimulation of the visceral ganglion causes arrest 

 of the heart. 



4. Stimulation of the cerebral ganglion produces no effect. 



5. Stimulation of nerves passing from the visceral ganglion to 

 the heart gives results comparable in every way to those obtained 

 from stimulation of the vasrus in the vertebrates, viz : lone after- 



<_> o 



effects of strong stimulation, and typical escape from weak 

 stimulation. 



6. No evidence of acceleration was ever present. 



Definitely localized cardiac organs are found in no group of ani- 

 mals generally considered lower than the lamellibranch molluscs. 

 It would therefore seem that, notwithstanding one or two doubt- 

 ful exceptions, cardiac muscle, wherever found, does not perform 

 its functions entirely independent of inhibitory influences of the 

 central nervous system. 



July 2-j. The Relation Between the Solution Tension and Physi- 

 ological Action of the Elements. By ALBERT P. MATHEWS. 

 As already pointed out by Loeb and the author, there is a 

 relationship between the valence of an ion and its physiological 

 action. For the motor nerve anions with three charges are some- 

 what more than three times as powerful stimulants as anions with 

 one charge. There are, however, for other tissues wide diver- 

 gencies from this rule, particularly for the cathions. For ex- 



