64 (234) Society for Experimental Biology and Medicine. 



1. In passing from the heart to the periphery the dicrotic eleva- 

 tion increases in distinctness and in the special case of the aortico- 

 femoral system the dicrotic elevation occurs lower on the catacrotic 

 limb of the fundamental wave. On the other hand as the arteries 

 decrease in size, the dicrotic elevation soon disappears, e. g., in the 

 thyroid, saphenous and so forth. Consequently there is in every 

 system of arteries (aorticofemoral, brachiocephalic and left sub- 

 clavian) a region lying somewhere between the aortic arch and the 

 periphery in which the dicrotic elevation is maximal. 



2. In the aorticofemoral system the side pulse shows a maximal 

 dicrotic wave between the origin of the renal and that of the deep 

 femoral artery ; in the brachiocephalic system, between the origin 

 of the carotids and that of the vertebral or thyroid artery ; in the 

 left subclavian system the dicrotic wave is less pronounced in the 

 mammary than in the vertebral artery and consequently the 

 maximum in question must lie central from the origin of the former 

 artery. In the case of the end pulse, the region of the maximal 

 dicrotic wave is in or peripheral to the brachial, femoral and carotid 

 arteries but it is impossible to say whether the maximum occurs 

 in them or peripheral to them, because they were the most peri- 

 pheral of the arteries examined in this connection. 



3. In the femoral pulse wave the dicrotic elevation is normally 

 much more distinctly marked and begins much lower on the cata- 

 crotic limb of the fundamental wave than is the case with the 

 carotid pulse. 



4. Certain operative procedures (namely determination of the 

 blood pressures in various deep seated arteries after opening the 

 thoracic or abdominal cavity) cause the predicrotic notch in the 

 femoral to become more and more pronounced so that ultimately 

 the dicrotic wave appears as an elevation on the ascending limb of 

 the fundamental wave which immediately follows. In the case of 

 the carotid pulse this effect of operation is very rarely seen. As 

 yet the writer is unable to offer any satisfactory explanation of 

 these local variations in the character of the dicrotic elevation. 

 He has however begun an investigation with the view of elucidating 

 this question. 



