100 



Scientific Proceedings (57). 



Spleen infusion had no effect on volume of the gland. The 

 same may be said for orchitic extract. 



Parathyroid infusion decreases blood-pressure for a short time, 

 also decreases pancreatic volume for a short period, and then 

 greatly increases it. 



Infusion of corpus luteum decreases blood-pressure momen- 

 tarily and increases the volume of the pancreas. 



Pineal infusion increases the flow of pancreatic juice. 



60 (877) 



The origin of the cardiac impulse in the turtle's heart. 



(Preliminary communication.) 

 By W. J. Meek and J. A. E. Eyster. 



[From the Physiological Laboratory of the University of Wisconsin.] 



Recent work has emphasized the sinoauricular node as the 

 seat of origin of the cardiac impulse in the normal heart. This 

 structure must be considered anatomically as forming a connection 

 or junction between remains of the primitive sinus, which has 

 disappeared as a separate chamber in the mammalia, and the 

 auricle. Since indications of the presence of a sinoauricular 

 junction, composed of tissue differentiated histologically from the 

 ordinary cardiac muscle, is found not only in those hearts in which 

 the sinus has disappeared as a separate chamber, but also in the 

 amphibia and reptiles, where a separate sinus venosus is present, 

 it becomes of essential importance to determine whether or not 

 in these animals the heart beat arises as it does in the mammalian 

 heart, that is in the sinoauricular junction. This problem may be 

 attacked by determining that region which shows initial electric 

 negativity when connected with the string galvanometer. We 

 have had this problem in mind for some time, but have been 

 unable to proceed with it because of the difficulty in securing 

 material with sufficiently large hearts to test this point satis- 

 factorily. Recently we have been able to secure one large turtle 

 in which the heart was of sufficient size. In this the right half 

 of the sinus was 35 millimeters long and 20 millimeters wide at its 



