88 



A MANUAL OF PHYSIOLOGY 



one was in the right ventricle the other was in the auricle of the same 

 side. Each ampulla communicated by a separate tube in the common 

 stem of the instrument with a recording tambour, and the writing 

 points of the two tambours were arranged in the same vertical line. 

 When any change in the blood-pressure takes place, the degree of 

 compression of the ampullae is altered, and the change is transmitted 

 along the air-tight connections to the recording tambours. Simul- 

 taneous records of the changes in the blood-pressure in the right 

 auricle and ventricle obtained in this way indicate a sudden rise of 

 the auricular pressure corresponding with the auricular systole, 

 followed bv a sudden fall (Fig. 24) . This is represented on the ven- 

 tricular curve by a 

 smaller elevation, 

 which shows that the 

 pressure in the ven- 

 tricle has been raised 

 somewhat by the 

 blood driven into it 

 from the auricle. 

 Then follows imme- 

 diately a great and. 

 abrupt increase of ven- 

 tricular pressure, the 

 result of the systole 

 of the ventricle. The 

 beginning of this ele- 

 vation is synchronous 

 with the beginning of 

 the first sound ; it re- 

 mains for some time 

 at the maximum, and 

 then the curve sud- 

 denly sinks as the 

 ventricle relaxes. On 

 the descending limb 

 there is a slight ele- 

 vation, due, as Marey 

 supposed, to the clo- 

 sure of the semilunar 

 valves, which causes 

 a better-marked and 

 simultaneous eleva- 

 tion in the curve of 

 aortic pressure when 

 sound passed into the aorta 

 the auricular and ventricular 



FIG. 28. COMPARISON OF PRESSURE - CURVES OF 

 LEFT AURICLE, LEFT VENTRICLE,^ AND AORTA 

 (v. FREY). 



Recorded by elastic manometers with air trans- 

 mission. The ventricular curve shows a ' peak.' 



this is registered by means of a 



through the carotid artery. Both 



curves now begin again to rise slowly, showing a gradual increase 



of pressure as the blood flows from the great veins into the auricle, 



and through the tricuspid orifice into the ventricle. This slow rise 



continues till the next auricular systole. 



It is probable that some of the smaller elevations on the curves 

 of Chauveau and Marey, and particularly that which they 

 associated with the closure of the semilunar valves, were due to 

 the oscillations of their apparatus. For it is a remarkable 



