78 ON THE MOTION OP THE BLOOD. 



the segment of ;i circle, when the apex moving atlantad and 

 sinistrad, is made to strike against the left side. The same kind 

 of motion having also been observed by the celebrated Haller, in 

 distending the left or systemic auricle, it must follow, that the 

 stroke which is given to the side, may be the effect of two distinct 

 causes, either acting separately, or in combination ; but acting 

 on a heart obliquely situated, as ours is, in the cavity of the 

 thorax, where the aspect of the base is atlantad and dextrad, and 

 that of the apex sinistrad and sacrad. In combination, as the 

 first of the two, by removing the pressure, will facilitate the. in- 

 flux of the venous blood into the left or systemic auricle, which 

 is situated dorsad ; so the second, by the influx of blood into the 

 auricle, will contribute in its turn to facilitate the circular motion 

 of the heart, proceeding from the arteries." * 



(B) It is commonly believed, that the pulse of every person is 

 quicker in the evening than in the morning, and some have sup- 

 posed an increase of quickness also at noon. Upon these sup- 

 positions Cullen builds his explanation of the noon and evening 

 paroxysms of hectic fever, f regarding them as merely aggrava- 

 tions of natural exacerbations. The existence of the noon pa- 

 roxysms is doubtful, and the evening one cannot be so explained, 

 if the writer of a paper in the Edinbugh Journal is correct. $ 

 His observations show the pulse to be slower in the evening, 

 and^tjuicker in the morning. 



(C) The heart, however, of frogs, for instance, contracts and 

 relaxes alternately, for a length of time, when out of the body 

 and destitute of blood. 



(D) The influence of this vacuum first pointed out by 

 Dr. Andrew Wilson, and conceded by John Hunter, has been 

 lately very ably displayed by Dr. Carson of Liverpool. 



The quantity of the blood, the length of its course, and the 



* The Muscular Motions of the Human Body. p. 567. 



\- Practice of Physic. 



t Robert Knox, M.D. Edinburgh Medical atid Surgical Journal. 1815. 



.1n Inquiry i/ifo (fie Causes of the Motion of the Blood. 1815. 



