CIRCULATION. 417 



Absolute Range of Pressure within the Ventricles and its Signifi- 

 cance. In dealing with the work done by the contracting ventricles (p. 398) 

 we have seen that the mercurial manometer, as used for studying the pressure 

 within the arteries, is quite unable to follow the changes of the intra-ventric- 

 ular pressure ; but that, by the intercalation of a valve, this instrument can be 

 converted into a useful " maximum manometer " for the measuring and record- 

 ing of the highest pressure occurring within the ventricle during a given time 

 that is, during a certain number of cycles. It must now be added that by a 

 simple change of valves this same instrument can at any moment be changed 

 into a " minimum manometer." l We can thus, by means of the modified mer- 

 curial manometer, learn with fair correctness the extreme range of pressure 

 within the ventricles. As instances of the extent of this range, two observa- 

 tions may be cited upon the left ventricle of the dog, the chest not having been 

 opened. In one animal the maximum was found to be 234 millimeters of mer- 

 cury, the maximum pressure in the aorta being 212 millimeters; and the min- 

 imum in the left ventricle was 38 millimeters that is to say, 38 millimeters 

 less than the pressure of the atmosphere, the minimum pressure in the aorta 

 being 120 millimeters. In a second dog the figures were 176 and -30 milli- 

 meters for the ventricle, the aortic range being from 158 to 112 millimeters. 2 

 In the right ventricle of the dog such ranges as from 26 to 8 millimeters, 

 from 72 to 25, and various intermediate values, have been noted, both in 

 the unopened and the opened chest. 3 For reasons already stated (p. 395) no 

 trustworthy figures can be given for the pressures in the pulmonary artery ; 

 but they can never fail to be less than the highest pressures within the right 

 ventricle. 



The range of pressure, therefore, within either ventricle is in sharp contrast 



Archiv fur die gesammte Physiologie, as follows: "Zur Technik der Untersuchung des Blut- 

 druckes," 1888, vol. 43, p. 399. " Technische Mittheilungen," 1890, vol. 47, p. 1. " Ueber 

 den Ursprungsort der sekundaren Wellen der Pulscurve," vol. 47, p. 17. " Technische Mit- 

 theilungen," 1891, vol. 49, p. 29. " Ueber den Zusammenhang zwischen Herzthatigkeit und 

 Pulsform," vol. 49, p. 51. " Kritik des Lufttransmissionsverfahrens," 1892, vol. 53, p. 281. 

 " Vergleichende Prufung der Tonographen von Frey's und Hiirthle's," 1893, vol. 55, p. 319. 

 K. Hiirthle : " Orientirungsversuche iiber die Wirkung des Oxyspartein auf das Herz," Archiv 

 fur experimentelle Pathologic und Pharmakologie, 1892, vol. xxx. p. 141. W. T. Porter : " Researches 

 on the Filling of the Heart," The Journal of Physiology, 1892, vol. xiii. p. 513. " A New Method 

 for the Study of the Intracardiac Pressure Curve," Journal of Experimental Medicine, vol. i., 

 No. 2, 1896. M. von Frey und L. Krehl: " Untersuchungen iiber den Puls," Archiv fur 

 Anatomie und Physiologic, Physiologische Abtheilung, 1890, p. 31. M. von Frey: "Die Unter- 

 suchung des Pulses," Berlin, 1892. "Das Plateau des Kammerpulses," Archiv fur Anatomie 

 und Physiologie, Physiologische Abtheilung, 1893, p. 1. " Die Ermittlung absoluter Werthe fiir 

 die Leistung von Pulsschreibern," Archiv fiir Anatomie und Physiologie, Physiologische Abtheil- 

 ung, 1893, p. 17. " Zur Theorie der Lufttonographen," Archiv fiir Anatomie und Physiologie, 

 Physiologische Abtheilung, 1893, p. 204. " Die Erwarmung der Luft in Tonographen," Cen- 

 tralblatt fiir Physiologie vom 30 Juni 1894, Heft 7. 



1 F. Goltz und J. Gaule : " Ueber die Druckverhaltnisse im Innern des Herzens," Pfliiger's 

 Archiv fur die gesammte Physiologie, 1878, xvii. p. 100. 



2 S. de Jager : " Ueber die Saugkraft des Herzens," Pfliiger's Archiv fur die gesammte Physi- 

 ologie, 1883, Bd. xxxi. p. 491. 



3 S. de Jager: Loc. cit., pp. 506, 507; Goltz und Gaule: Loc. cit., p. 106. 



27 



