516 



SCIENCE 



[N. S. Vol. XXIX. No. 743 



by an interval of about 0.18 second. It is caused 

 by the contraction of the auricle. In some 

 tracings the a wave is very prominent, greatly 

 overshadowing the succeeding c wave. This was 

 noted particularly in patients with more or less 

 decompensation, though it is not pathognomonic 

 of such conditions. 



The c wave occurs almost simultaneously with 

 the carotid pulse and in some instances it is 

 caused by a transmitted arterial pulsation. The 

 earlier writers, especially Francois Franck, Fred- 

 ericq and Gerhardt regarded the o wave as a true 

 venous wave, but Mackenzie and Wenckebach be- 

 lieve that it is always a carotid pulse. Eecent 

 investigations, however, tend to show the correct- 

 ness of the earlier views; for, (1) the c wave can 

 often be recognized by inspection as being present 

 in the veins themselves, (2) it often precedes the 

 carotid pulse by about 0.02 second, (3) it has a 

 different form, (4) it can occasionally be dem- 

 onstrated on liver tracings, and (5) in pathologic 

 venous tracings, especially from cases of auricular 

 paralysis, the c wave on the jugular differs in size 

 from the radial pulse, often being largest when 

 the radial is smallest. In most tracings, there- 

 fore, the wave is of venous origin; when of 

 arterial origin, this is generally indicated by its 

 form. 



The venous o wave is probably to be referred 

 back to the momentary increase in intra-auricular 

 pressure which occurs at the onset of ventricular 

 systole. This wave of increased pressure appears 

 somewhat later in the neck on account of the 

 slow transmission of venous waves. 



The negative wave following the a wave is un- 

 doubtedly due to auricular diastole. That fol- 

 lowing the wave may also be explained in part 

 by auricular diastole; but it is evident (1) from 

 heart block tracings and (2) from tracings of 

 auricular paralysis from man and from animals 

 that ventricular systole alone is capable of causing 

 a negative wave in the venous pulse just after the 

 wave. This is caused by the descent of the 

 ventricular base during systole, which opens up 

 the auricle on its attachments to the great veins. 



Tracings from a patient with palpitation showed 

 a very marked c wave and a very marked depres- 

 sion immediately following. As other venous 

 waves were merely indicated on the tracing, it 

 seems probable that the earlier movements of the 

 ventricle during systole were executed with un- 

 usual speed. 



The V wave appears in the neck just after the 

 time of the dicrotic notch on the arterial pulse. 



Owing, however, to the slow transmission of 

 venous waves the v wave begins in the heart at a 

 somewhat earlier period, probably in late systole, 

 and it is terminated there by the opening of the 

 tricuspid valves. It is probably due partly to a 

 replacement of the base of the ventricle toward 

 the auricle at the onset of diastole. It is also due 

 in part to the accumulation of blood in the auricle 

 during the closing of the tricuspid valves. The 

 V wave is accentuated in conditions of auricular 

 stasis especially in tricuspid insufBcienoy and 

 auricular paralysis. 



The negative wave following the v wave is due 

 to the opening of the tricuspid valves and the 

 consequent flow of blood toward the ventricle. It 

 is especially pronounced in conditions of auricular 

 stasis. In slowly acting hearts this negative wave 

 is often followed by a shoulder on the venous 

 tracing which seems to be due to a recoil from the 

 rapid filling of the ventricle. 



William J. Gies, 



Secretary 



SOCIETIES AND ACADEMIES 



THE WASHINGTON ACADEMY OP SCIENCES 



Db. Alfebd G. Mayeb, of the Carnegie Institu- 

 tion of Washington, delivered an address before 

 the Washington Academy of Sciences Tuesday 

 evening, February 23, on " The Tortugas Marine 

 Laboratory, its Scope and Aims." Dr. Mayer 

 kindly furnished the following abstract of his 

 address : 



"The lecturer called attention to the fact that 

 this laboratory is the only permanent marine 

 station within the American tropics, and that the 

 generous support accorded to it by the Carnegie 

 Institution of Washington had enabled it to de- 

 velop into the best equipped marine laboratory 

 in the tropical world. 



" The seven Tortugas Islands are out in the 

 Gulf of Mexico, seventy miles west of Key West, 

 and consist of coarse wave-washed and wind- 

 blown fragments of marine shells, which afford 

 no soil suitable for the growth of mangroves; 

 and thus the laboratory is unique in being the 

 only place on the seaboard of Florida which is 

 free from endemic mosquitoes in summer. 



" Along the mainland coast of southern Florida 

 the winds cause the waters over the coral flats to 

 be churned into a silky mass of suspended silt, 

 which is fatal to pelagic life, but at Tortugas, 

 owing to the great area of deep ocean water in 

 their neighborhood and the small size of the coral 



