THE CIRCULATION OF THE BLOOD. 949 
That these are genuine, answer of real and corresponding 
elevations of the arterial wall and of the blood-current itself, 
seems probable from 
the study of a hemau- 
togram, The latter may 
be obtained by allowing 
the blood from a cut 
artery to spurt against 
a piece of paper drawn 
in front of the blood- 
stream. It is also as- 
[a] 
& ee 
ee 
teh 
(i eee 
Obesccas sou 
Gl ss 
th---- 
serted that by a tele- 
phonic connection with 
an artery both the pri- 
Fig. 220.—Pulse-curve from radial of man. Taken with 
mary pulse-wave and ‘an extra-vascular pressure of 70 mm. of mercury. 
. A The curved interrupted lines show the distance from 
the dicrotic wave may one another in time of the chief phases of the pulse- 
wave. a, tl e commencement, ant the close of ex- 
be heard. More rarely peneiat ~ Brtery 5 De Erediorptie okt d, dicrotic 
there are interruptions fhe postdicrotie note)? POS lerotte rests J, 
in the first upward 
curve, termed anacrotic curves, as distinguished from those in 
the downward curve known as katacrotic. 
It has been generally admitted that the first marked upward 
curve is due to the systolic 
shock. 
The following are, in 
Fie. 221.—Anacrotic pulse-tracing from carotid of brief, some of the views 
seks that have been entertained 
in regard to the minor features of the tracings: 
(a.) That the predicrotic wave-crest is owing to the sudden 
arrest of the flow from the ventricle. 
(o.) That the dicrotic wave is a wave of oscillation. 
wll 
Fie. 222.—Two grades of marked dicrotism in radial pulse of man (typhoid fever). 
(c.) That it is a wave of reflection from the periphery. 
(d.) That it is caused by the sudden closure of the aortic 
valves, 
It appears to be now pretty well agreed that the theory of 
reflection is untenable on physical principles; that a high 
blood-pressure tends to render the katacrotic markings less 
