442 VETERINARY PHYSIOLOGY 



this may be higher than the primary crest, producing the 

 condition known as the anacrotic pulse. The relatively 

 high intra-arteriai pressure in such a case prevents the 

 development of a well-marked dicrotic wave. 



In extreme cases of this kind, when the arterial walls are 

 very tense, they may recover in an irregular jerky manner, 

 and may give rise to a series of katacrotic crests producing a 

 polycrotic pulse (fig. 186, s). 



From what has been said, it will be seen that a study of 

 the pulse wave gives most valuable information as regards 

 the state of the circulation, and the physician constantly 

 makes use of the pulse in diagnosis. 



Palpation of the Pulse. — On placing the finger on the 

 artery the points to determine are — 



1st. The rate of the pulse — i.e. the rate of the heart's 

 action. 



2nd. The rhythm of the pulse — i.e. of the heart's action, 

 as regards — (1) Strength of the various beats. — Normally 

 the beats differ little from one another in force — since the 

 various heart-beats have much the same strength. Respira- 

 tion has a slight effect which will afterwards be considered 

 (see p. 535). In pathological conditions great differences 

 in the force of succeeding pulse waves may occur. (2) 

 Ti'ine relationshij) of the beats. — Normally the beats follow 

 one another at regular intervals — somewhat shorter during 

 inspiration — somewhat longer during expiration. In patho- 

 logical conditions great irregularities in this respect may 

 occur. 



Srd. The volume of the pulse wave. Sometimes the 

 wave is high and greatly expands the artery — sometimes it 

 is less high and expands the artery less. This is a measure 

 of the difference between systolic and diastolic pressure. 

 The former condition is called a full pulse (2)ulsus 'pleniis), 

 the latter a small pulse (pulsus ijarvus). The fulness of 

 the pulse depends upon two factors : — 1st. The average 

 tension in the arteries between the pulse-beats — the diastolic 

 pressure. If this is high, the walls of the artery are already 

 somewhat stretched, and therefore the pulse wave may expand 



