dicrotic wave appear first when a weight of 220 to 300 grammes is used. (5) The
rapidity of the pulse changes with increasing weight, the time occupied by the
ascent becoming shorter, the descent becoming longer. (6) The height of the entire
curve decreases as the weight increases. In every sphygmogram the pressure
under which it was obtained ought always to be stated.
In Fig. 66, A, B, C, D, are curves obtained from the radial artery of a healthy
student. The pressure exerted upon the artery for A was 100; B, 170; C, 220;
and D, 240 grms. The time occupied by the various events was :
1-2, . . .
1-a, . . .
1-3, . , .
1-4, ,. . .
1-5, V v .
1-b, . . .
1-6, .... . -
If pressure be exerted upon an artery for a long time the strength of the pulse is
gradually increased. If, after subjecting an artery to considerable pressure, a
lighter weight be used, not unfrequently the pulse-curve assumes the form of a
dicrotic pulse, owing to the greater development of the dicrotic elevation. When
strong pressure is applied, the blood is forced to find its way through collateral
channels. When the chief artery ceases to be compressed, the total area is, of
course, considerably and suddenly enlarged, which results in the production of a
dicrotic elevation. Fig. 58, X, is such a dicrotic curve obtained after considerable
pressure had been applied to the artery.
76, Rapidity of Transmission of Pulse-Waves,
The pulse-wave proceeds throughout the arterial system from the
root of the aorta, so that the pulse is felt sooner in parts lying near the
heart than in the peripheral arteries. E. H. Weber calculated the
rate of the pulse- wave as 9*240 metres [28J feet] per sec. from the
difference in time between the pulse in the external maxillary artery
and the dorsal artery of the foot. Czermak showed that the elasticity
was not equal in all the arteries, so that the velocity of the pulse-wave
cannot be the same in all. The pulse-wave is propagated more slowly
in the arteries with soft extensile walls than in arteries with resistant
and thick walls, so that it is transmitted more rapidly in the arteries
of the lower extremities than in those of the upper. It is still slower
77. Propagation of the Pulse- Wave in Elastic
Waves similar to the pulse may be produced in elastic tubes. (1) According to
E. H. Weber the velocity of propagation of the waves is 11 '295 metres per sec.;
PROPAGATION OF PULSE-WAVES IN ELASTIC TUBES.
according to Bonders, 11-14 metres (34 - 43 feet). (2) According to E. H. Weber
increased internal tension causes only an inconsiderable decrease ; Rive found a
great decrease ; Ponders found no obvious difference ; while Marey found an increased
velocity. (3) Bonders found the velocity to be the same in tubes, 2 mm. in dia-
meter, as in wider tubes, but Marey believes that the velocity varies when the
diameter of the tube changes. (4) The velocity is less the smaller the elastic
coefficient. (5) The velocity increases with increased thickness of the wall, while
it diminishes when the specific gravity of the fluid increases.
Moens has recently formulated the following laws as to the velocity of propaga-
tion of waves inelastic tubes: (1) It is inversely proportional to the square root
of the specific gravity of the fluid. (2) It is as the square root of the thickness
of the wall, the lateral pressure being the same. (3) It is inversely as the square
root of the diameter of the tube, the lateral pressure being the same. (4) It is
as the square root of the elastic coefficient of the wall of the tube, the lateral
pressure being the same (Valentin).
Experiments With Caoutchouc Tubes. For this purpose Landois employs
the following apparatus (Fig. 67): A large tuning-fork, A (35 cmtr. long), carries
on one of its arms a glass-plate, P (25 cmtr. long, and 5 cmtr. broad), while the other
arm is weighted, G. The tuning-fork is fixed by an iron holder, T, to a movable
piece of wood which can be pushed along with the hand in a groove on a support
H, H. When the glass-plate is smoked, the curved needle of the angiograph
writes its movements upon it. The fork, when it vibrates, makes little teeth in
the curve, and the value of each vibration is estimated beforehand. Every com-
plete vibration in this instrument is equal to 0*01613 sec.
Velocity of the Waves in Elastic Tubes filled with Water or Mercury.
Take a soft extensible elastic tube, A, 8'80 metres long, 1 mm. thick, and
Instrument for measuring the velocity of the pulse- wave in an elastic tube con-
taining water or mercury A, tuning-fork; B, ampulla; A, elastic tube; P,
glass-plate smoked; Q, manometer; x, pad of lever of angiograph; writiog-
. style, D.
154 VELOCITY OP THE PULSE-WAVE IN MAN.
7 mm. diameter. If 1 metre of the tube is weighted with 1 kilo, it elongates 68
cmtr. An ampulla, B, capable of containing 50 cmtr., is fixed to one end of the
tube, while to the other end of the ampulla is fixed a mercurial manometer, Q.
Pulse-curve from an elastic tube registered upon a plate attached to a vibrating
The tube, A, is shut close to the ampulla every time the pressure is mea-
sured, in order to obviate the occurrence of oscillation in the mercury. A certain
portion of the tube, say 8 metres, is measured. The beginning, a, and end, &,
of this stretch of tubing are placed under the pad, x , of the angiograph. When
a positive wave is produced by compressing the ampulla, the writing-lever is raised
twice, the first time when the wave passes the first part of the tube, a, under the
pad, and the second time when the end part of the tube, b, is distended by the
wave. The curve obtained is shown in Fig. 67, in which the two elevations,
1 and 2, are obvious. The time between the two may be ascertained by counting
the number of vibrations of the tuning-fork. The experiments gave the following
(A.) The velocity of the wave is 11 "809 metres per sec.
(B.) The intra-vascular pressure has a decided influence on the velocity: thus,
in the tube, A, with 18 cmtr. (Hg.) pressure, the velocity per metre = 0*093 sec.,
while with 21 cmtr. pressure (Hg.) = 0*095 sec. per metre.
(C.) The specific gravity of the liquid influences the velocity of the pulse-wave.
In mercury the wave is propagated four times more slowly than in water (Marey
(D.) The velocity in a tube which is more rigid and not so extensile is greater
than in a tube which is easily distended.
78. Velocity of the Pulse-Wave in Man,
Landois obtained the following results in a student whose height was 174 centi-
metres : Difference between carotid and radial = 0*074 sec. (the distance being
taken as 62 centimetres); carotid and femoral =0*068 sec.; femoral (inguinal
region) and posterior tibial* 0*097 sec. (distance estimated at 91 centimetres).
The velocity of the pulse-wave in the arteries of the upper extre-
mities 9*43 metres per sec., and in those of the lower extremity 9*40
metres per second. The velocity is greater in the less extensible arteries
VELOCITY OF" T&E PULSE-WAVE IN MAN.
of the lower extremities than in those of the upper limb. For the same
reason it is less in the peripheral arteries and in the yielding arteries
of children (Czermak).
E. H. Weber estimated the velocity at 9 '24 metres per sec.; Garrod, 9 -10 '8
metres; Grashey, 8' 5 metres; Moens, 8*3 metres, and with diminished pressure
during Valsalva's experiment (p. 112) 7'3 metres.
In animals, hsemorrhage (Haller), slowing of the heart produced by stimulation
of the vagus (Moens), section of the spinal cord, deep morphia-narcosis, and dilata-
tion of blood-vessels by heat, produce slowing of the velocity, while stimulation of
the spinal cord accelerates it (Grunmach).
The wave-length of the pulse-wave is obtained by multiplying the
duration of the inflow of blood into the aorta^O'08 to 0*09 sees,
(p. 86) by the velocity of the pulse-wave.
Method. Place the knobs of two tambours (Fig. 52) upon the two arteries to
be investigated, or place one over the apex-beat and the other upon an artery.
These receiving tambours are connected with two registering tambours, as in
Brondgeest's pansphygmograph ( 67, Fig. 52) so that their writing-levers are
directly over each other, and so arranged as to write simultaneously on one vibrating-
plate attached to a tuning-fork. [Or they may be made to write upon a revolving
cylinder, whose rate of movement is ascertained by causing a tuning-fork of a
known rate of vibration to write under them.] In Fig. 68, H is the curve obtained
from the heart, and C from the radial artery. The apparatus is improved by using
rigid tubes and filling them with water, in which all impulses are rapidly communi-
cated. In arteries which are distant from each other, or in the case of the heart
and an artery, the two knobs of the receiving tambours may be connected by means
of a Y-tube with one writing-lever. In Fig. 68, B is a curve from the radial artery
taken in this way. In it v H P indicates contraction of the ventricle ; H, the
apex of the ventricular contraction ; P, the primary apex of the radial curve ; v, the
A, curve of radial artery on a vibrating surface (1 vib. =0*01613 sec.) ; P, apex
of curve ; e, e, elastic vibrations ; R, dicrotic wave ; B, curve of same radial
taken along with the heart-beat ; v, H, P, contraction of the ventricle ; H,
curve of the heart-beat ; C, of the radial artery, taken simultaneously. The
arrows indicate the identical points in both curves. In B, v to p - 9 vibrations.
156 FURTHER PULSATILE PHENOMENA.
beginning of the ventricular contraction ; p, of the radial pulse. A is the curve of
the radial artery alone. From these curves, as well as from H and C, it is evident
that in this instance 9 vibrations occur between the beginning of the ventricular
contraction (in H at 22) until the beginning of the pulse in the radial artery (in C
at 13), so that 0* 15 sec. elapses between these two events (1 vibration =0*01613 sec.).
In Fig. 69 the difference between the carotid and the posterior tibial pulse =
Curves of the carotid and posterior tibial taken simultaneously with Brondgeest's
pansphygmograph writing upon a vibrating plate, attached to a tuning-fork.
, The arrows indicate the identical moment of time in each curve.
Pathological. In cases of diminished extensibility of the arteries, e.g., in
atheroma (p. 127), the pulse-wave is propagated more rapidly. Local dilatations of
the arteries, as in aneurisms, cause a retardation of the wave, and a similar result
arises from local constrictions. Relaxation of the walls of the vessels in high
fever retards the movement (Hamernjk).
79. Further Pulsatile Phenomena.
1. In the mouth and nose, when they are filled with air, and the glottis
closed, pulsatile phenomena (due to the arteries in their soft parts), may be found
communicating a movement to the contained air. The curves obtained are
relatively small, and closely resemble the curve of the carotid. A similar pulse
is obtained in the tympanum with intact membrana tympani, and when the
eoft parts of the tympanum are congested (Schwartze, Troltsch).
2. Entoptical Pulse, After violent exercise, an illumination corresponding to
each pulse-beat, occurs on a dark optical field. When the optical field is bright,
an analogous darkening occurs (Landois). The ophthalmoscope occasionally reveals
pulsation of the retinal arteries ( Jager), which becomes marked in insufficiency of
the aortic valves (Quincke, O. Becker, Helfreich).
3. Pulsatile Muscular Contraction. The orbicularis palpebrarum muscle
contracts under similar conditions synchronously with the pulse ; and it is perhaps
due to the pulse-beat exciting the sensory nerves reflexly. The brothers Weber
found that not unfrequently while walking, the step and pulse gradually and in-
4. When the legs are crossed as one sits in a chair, the leg which is supported
is raised with each pulse-beat, and it gives also a second or dicrotic elevation.
5. If, while a person is quite quiet, the incisor teeth of the lower jaw be made
just to touch the upper incisors very lightly, we detect a double beat of the lower
VIBRATIONS COMMUNICATED TO THE BODY BY THE HEART. 157
against the upper teeth, owing to the pulse-beat in the external maxillary artery
raising the lower jaw. The second elevation is due to the closure of the semi-lunar
valves, and not to a dicrotic wave.
6. Brain and Fontanelles. The large arteries at the base of the brain com-
municate a movement to it, while similar movements occur with respiration rising
during expiration and falling during inspiration. These movements are visible
in the fontanelles of infants. The respiratory movements depend upon variations in
the amount of blood in the veins of the cranial cavity, and also upon the respiratory
variations of the blood-pressure.
7. Amongst pathological phenomena, are the beating in the epigastrium, as in
hypertrophy of the right or left ventricle, caused, it may be, by deep insertion of
the diaphragm, and it may be partly by the beating of a dilated abdominal aorta or
Abnormal dilatations (aneurisms) of the arteries cause an abnormal pulsation,
while theyproducea slowing inthe velocity of the pulse- wave in the corresponding artery.
Hence the pulse appears later in such an artery than in the artery on the healthy
side. Hypertrophy and dilatation of the left ventricle cause the arteries near the
heart to pulsate strongly. In the analogous condition of the right ventricle, the beat
of the pulmonary artery may be seen and felt in the second left intercostal space.
80. Vibrations communicated to the Body by the
action of the Heart.
The beating of the heart and large arteries communicates vibrations to the body
as a whole, but the vibration is not simple but compound.
Gordon was the first to represent this pulsatory vibration graphically. If a
II, Elastic support for registering the molar motions of the body K, a wooden
box ; B, feet of patient ; p, cardiograph ; a, b, elastic tubing. I, III Vibra-
tion curves of a healthy person. IV Similar curve obtained from a patient
suffering from insufficiency of the aortic valves and great hypertrophy of the
158 VIBRATIONS COMMUNICATED TO THE BODY BY THE HEART.
person be placed in an erect attitude in the scale of a large balance, the index
oscillates, and its movements coincide with the heart's movements.
Fig. 70, I, shows a curve obtained by Gordon, written directly by the index of
the spring balance. The lowest part of the curve corresponds to the systole of the
Landois employed the following arrangement : Take a long four-sided box, K,
open at the top, and arrange several coils, a, b, of stout caoutchouc tubing round
one end. A wooden board, B, smaller than the opening in the box, is so placed
that it rests with one end on the caoutchouc tubing, and with the other on the
narrow end of the box. The person to be experimented upon, A, stands vertically
and firmly on this board. A receiving tambour, p, is placed against the surface
of the board next the elastic tube, which registers the vibrations of the foot
support. Fig. Ill is a curve showing such vibrations, each heart-beat being followed
in this case by four oscillations. It corresponds to I. To ascertain the relations
and causes of these vibrations, it is necessary to obtain, simultaneously, a tracing
of the heart and the vibratory curve. For this purpose use the two tambours of
Brondgeest's pansphygmograph (p. 71), placing one nob or pad over the heart,
and the other on the foot-support, and allow the writing-tambours to inscribe their
vibrations on a glass-plate attached to a tuning-fork.
In the lower or cardiac impulse curve, Fig. 71, the rapidly-rising part is due to
the ventricular systole. It contains 8 vibrations (1 vib. =0*01613 sec.). The
beginning of the ventricular systole is indicated in the fig. by - 36 - 3 - 17.
If the corresponding numbers in the upper or vibratory curve are studied, it is
obvious that at the moment of ventricular systole the body makes a downward vibration,
i.e., it exercises greater pressure upon the foot - support. Gordon interprets his
curve as giving exactly the opposite result. This downward motion, however,
lasted only during 5 vibrations of the tuning-fork : during the last 3 vibrations,
corresponding to the systole, there is an ascent of the body corresponding to a less
pressure upon the foot-plate. When the ventricle empties itself, it undergoes a
movement in a downward and outward direction Gutbrodt's "reaction impulse."
The upper curve is the vibration-curve of a healthy person, and the lower one a
tracing of the apex beat.
In the upper curve analogous numbers are employed to indicate the vibrations
occurring simultaneously, viz., -28-11-10. The closure of the semi-lunar
THE BLOOD-CUKRENT. 159
valves is well marked in the three heart-beats at 20-20. This closure is
indicated in analogous points in both curves, after which there is a descent of the
foot-support, and this corresponds to the downward propagation of the pulse-wave
through the aorta to the vessels of the feet.
In insufficiency of the aortic valves, as shown in Fig. 70, IV, the vibration com-
municated to the body is very considerable.
81. The Blood-Current.
The closed and much-branched vascular system, whose walls are
endowed with elasticity and contractility, is not only completely
filled with blood but it is over-filled. The total volume of the blood is
somewhat greater than the capacity of the entire vascular system.
Hence it follows that the mass of blood must exert pressure on the
walls of the entire system, thus causing a corresponding dilatation of
the elastic vascular walls (Brunner). This occurs only during life;
after death the muscles of the vessels relax, and fluid passes into the
tissues, so that the blood-vessels come to contain less fluid and some
of the vessels may be emptied.
If the blood were uniformly distributed throughout the vascular
system and under the same pressure, it would remain in a position of
equilibrium (as after death). If, however, the pressure be raised in
one section of the tube the blood will move from the part where the
pressure is higher to where it is lower ; so that the blood-current is a
result of the difference of pressure within the vascular system. If either
the aorta or the venae cavae be suddenly ligatured in a living animal,
the blood continues to flow, gradually more slowly, until the difference
of pressure is equalised throughout the entire vascular system.
The velocity of the current will be greater the greater the difference
of pressure, and the less the resistance opposed to the blood-stream.
The difference of pressure which causes the current is produced by the
heart (E. H. Weber). Both in the systemic and pulmonary circulations
the point of highest pressure is in the root or beginning of the arterial
system, while the point of lowest pressure is in the terminal portion of
the venous orifices at the heart. Hence, the blood flows continually
from the arteries through the capillaries into the venous trunks.
The heart keeps up the difference of pressure required to produce
this result ; with each systole of the ventricles a certain quantity of
blood is forced into the beginning of the arteries, while at the same
time an equal amount flows from the venous orifices into the auricles
during their diastole (E. H. Weber).
Bonders added another important fact viz., that the action of the
heart not only causes the difference of pressure necessary to establish a
blood-current, but that it also raises the mean pressure within the vascular
160 THE BLOOD-CURRENT.
system. The terminations of the veins at the heart are wider and
more extensible than the arteries where they arise from the heart.
As the heart propels a volume of blood into the arteries equal to that
which it receives from the veins, it follows that the arterial pressure
must rise more rapidly than the venous pressure diminishes, since the
arteries are not so wide nor so extensible as the veins, Thus the total
pressure must also increase.
The volume of blood expelled from the ventricles at every systole
would give rise to a jerky or intermittent movement of the blood
stream 1. if the tubes had rigid walls, as in such tubes any pressure
exerted upon their contents is propagated momentarily throughout the
length of the tube, and the motion of the fluid ceases when the pro-
pelling force ceases. 2. The flow would also be intermittent in
character in elastic tubes if the time between two successive systoles
were longer than the duration of the current necessary for the compen-
sation of the difference of pressure caused by the systole. If the time
between two successive systoles be shorter than the time necessary to
equilibrate the pressure, the current will become continuous, provided
the resistance at the periphery of the tube be sufficiently great to bring
the elasticity of the tube into action. The more rapidly systole follows
systole, the greater becomes the difference of pressure, and the more
distended the elastic walls. Although the current thus produced is con-
tinuous, a sudden rise of pressure is caused by the forcing in of a mass
of blood at every systole, so that with every systole there is a sudden
jerk and acceleration of the blood-stream corresponding to the pulse
This sudden jerk-like acceleration of the blood-current is propagated
throughout the arterial system with the velocity of the pulse-wave :
both phenomena are due to the same fundamental cause. Every
pulse-beat causes a temporary rapid progressive acceleration of the
particles of the fluid. But just as the form-movement of the pulse is
not a simple movement, neither is the pulsatile acceleration a simple
acceleration. It follows the course of the development of the pulse-
wave. The pulse-curve is the graphic representation of the pulsatory
acceleration of the blood-stream. Every rise in the curve corresponds
to an acceleration, every depression to a retardation of the current.
Method. These facts are capable of demonstration by means of very simple
physical experiments. [Tie a Higginson's syringe to a piece of an ordinary gas-
pipe. On forcing water through the tube by compressing the elastic pump, the
water will flow out at the other end of the tube in jets, while during the intervals
of pulsation no water will flow out. As the walls of the tube are rigid, just as
much fluid flows out as is forced into the tube. If a similar arrangement be made,
and a long elastic tube be used, a continuous outflow is obtained, provided the
pulsations occur with sufficient rapidity and the length of the tube, or the resist-
CURRENT IN THE CAPILLARIES. 161
ance at its periphery, be sufficient to bring the elasticity of the tube into action.
This can be done by putting a narrow cannula in the outflow end of the tube, or
by placing a clamp on it so as to diminish the exit aperture. This apparatus
converts the intermittent flow into a continuous current.] The fire-engine is a
good example of the conversion of an intermittent inflow into a uniform outflow. The
air in the reservoir is in a state of elastic tension, and it represents the elasticity
of the vascular walls. When the pump is worked slowly, the outflow of the water
occurs in jets, and is interrupted. If the pumping movement be sufficiently rapid,
the compressed air in the reservoir causes a continuous outflow, which is distinctly
accelerated at every movement of the pump.
Current in the Capillaries. In the capillary vessels the pulsatile
acceleration of the current ceases with the extinction of the pulse-
wave. The great resistance which is offered to the current towards
the capillary area causes both to disappear. It is only when the
capillaries are greatly dilated, and when the arterial blood-pressure
is high, that the pulse is propagated through the capillaries into the
beginning of the veins. A pulse is observed in the veins of the sub-
maxillary gland after stimulation of the chorda tympani nerve, which
contains the vascular or vaso-dilator nerves for the blood-vessels of
this gland. If the finger be constricted with an elastic band so as to
hinder the return of the venous blood, and to increase the arterial
blood-pressure, while at the same time dilating the capillaries, an inter-
mittent increased redness occurs, which corresponds with the well-