INTRODUCTION. 7 



small pulses, the characters of which may be determined 

 from their names, also that form known as the intermittent, 

 either regular or irregular. In the latter case the beats 

 and intervals are uncertain, in the former at regularly 

 recurring intervals the pause is prolonged. The dicro- 

 tonous or double pulse is found in blood diseases ; it 

 consists in a double rise of the arterial wall for each beat 

 of the heart ; physiologists debate its nature ; it is a 

 symptom of importance. The thready pulse is extremely 

 small, and scarcely perceptible. The '^ running down ■'■' 

 pulse occurs just before death, especially in cases of 

 haemorrhage, and consists in rapid loss of force of beat, 

 with increasing frequency, until the pulse becomes imper- 

 ceptible. It is a very grave symptom. The 'Wenous 

 pulse '^ is a sign of which we shall make use when 

 treating of heart diseases. The sharp beat of the 

 '^ quick '^ pulse must be distinguished from the increase 

 in number of beats per minute characteristic of the 

 '^ frequent ^^ pulse. Sometimes the enlargements of the 

 artery vary in successive beats, then the pulse is termed 

 unequal, while extreme irregularity, and difficulty in 

 perception and appreciation of its characters constitute 

 the confused beat. The oppressed beat is prolonged and 

 not very marked, while the vessels are much distended. 

 We are not desirous of drawing attention here to the 

 exact method by which these conditions of the pulse are 

 produced, but will merely state that variations in frequency 

 and rapidity of beat are connected directly with the action 

 of the heart, and, therefore, especially dependent on states 

 of the nervous system and fever, inducing rapidity, 

 and certain brain disorders, reducing the beats below the 

 normal number per minute ; while the quick pulse shows 

 an irritable state of the heart, slowness of beat often de- 

 pends on impediment to egress of the blood. Hardness 

 and softness depend upon the tone of the arteries, which 

 consists in slight persistent contraction of their white 

 muscular fibres adapting them to their contents ; while 

 largeness or smallness depends upon the amount of blood 

 in the arteries, resulting from the state of supply from 



