plete passage of the corpuscle through the wall, and its farther motion in virtue of
its own amreboid movements. Hering observed that in large vessels with peri-
vascular lymph spaces, the corpuscles passed into these latter, hence cells are
found in lymph before it has passed through lymphatic glands. The cause of the
diapedesis is partly due to the independent locomotion of the corpuscles, and it is
partly a physical act, viz., a filtration of the colloid mass of the cell under the
force of the blood-pressure (Hering) in the latter respect depending upon the
intra-vascular pressure and the velocity of the blood-stream. Hering regards this
process, and even the passage of the coloured corpuscles through the vascular wall
as a normal process. The RED corpuscles pass out of the vessels when the venous
outflow is obstructed, which also causes the transudation of plasma through the
vascular wall. The plasma carries the coloured corpuscles along with it, and at
the moment of their passage through the wall they assume extraordinary shapes,
owing to the tension put upon them, regaining their shape as soon as they
pass out (Cohnheim).



190



MOVEMENT OF THE BLOOD IN THE VEINS.




This remarkable phenomenon was described by Waller in 1846. Cohnheim has

recently re-described it, and accord-
ing to him the out -wandering is a
sign of inflammation, and the
colourless corpuscles which accum-
ulate in the tissues are to be
regarded as true pus corpuscles,
which may undergo further in-
crease by division.
Stasis. When a strong stimulus
acts on a vascular part, hypersemic
redness and swelling occur. Micro-
scopic observation shows, that the
capillaries and the small vessels
Fig. 85. are dilated and overfilled with

Small vessel of themesentery of a frog, show- blood-corpuscles; in some cases a
ing the diapedesis of the colourless temporary narrowing precedes the
corpuscles w, w, vascular walls ; a, a, dilatation ; simultaneously the
Poiseuille's space ; r, r, red corpuscles ; velocity of the stream changes :
Z, I, colourless corpuscles adhering to rarely there is a temporary
the wall, and c, c, in various stages of acceleration, more frequently it
extrusion ; f, f, extruded corpuscles. becomes slower. If the action of

the stimulus or irritant be con-
tinued, the retardation becomes considerable, the stream moves in jerks, then
follows a to and fro movement of the blood-column a sign that stagnation has
taken place in other vascular areas. At last, the blood-stream comes completely
to a standstill STASIS and the blood-vessels are plugged with blood-corpuscles.
Numerous colourless blood-corpuscles are found in the stationary blood. Whilst
these various processes are taking place, the colourless corpuscles more rarely
the red pass out of the vessels. Under favourable circumstances the stasis may
disappear. The swelling which occurs in the neighbourhood of inflamed parts is
chiefly due to the exudation of plasma into the surrounding tissues. [The vapour
of chloroform causes hypersemia of the web (Lister).]



96. Movement of the Blood in the Veins.

As already mentioned, in the smallest veins coming from the
capillaries, the blood-stream is more rapid than in the capillaries them-
selves, but less so than in the corresponding arteries. The stream is
uniform, and if no other conditions interfered with it, the venous-
stream towards the heart ought to be uniform, but many circumstances
affect the stream in different parts of its course. Amongst these are :
(1) The relative laxness, great distensibility, and the ready compressibility
of the walls, even of the thickest veins. (2) The incomplete filling
of the veins, which does not amount to any considerable distension
of their walls. (3) The numerous and free anastomoses between
adjoining veins, not only between veins lying in the same plane, but
also between superficial and deep veins. Hence, if the course of the
blood be obstructed in one direction, it readily finds another outlet.



MOVEMENT OF THE BLOOD IN THE VEINS. 191

(4) The presence of numerous valves which permit the blood-stream to
move only in a centripetal direction (Fabricius ab Aquapendente).
They are absent from the smallest veins, and are most numerous in
those of middle size.

Law of the Position. Of Valves. The venous valves always have two
pouches, and are placed at definite intervals, which correspond to the 1, 2, 3, or
n 111 power of a certain "fundamental distance," which is = 7mm. for the lower
extremity and 5*5 mm. for the upper. Many of the original valves disappear. On
the proximal side of every valve a lateral branch opens into the vein, while on the
distal side of each branch lies a valve. The same is true for the lymphatics
(K. Bardeleben).

Effect of Pressure. As soon as pressure is applied to the veins, the
next lowest valves close, and those immediately above the seat of
pressure open and allow the blood to move freely toward the heart.
The pressure may be exerted from without, as by anything placed
against the body; the thickened contracted muscles, especially the muscles
of the limbs, compress the veins. That the blood flows out of a
divided vein more rapidly when the muscles contract, is shown during
venesection. If the muscles are kept contracted, the venous blood
passing out of the muscles collects in the passive parts e.g., in the
cutaneous veins. The pulsatile pressure of the arteries accompanying
the veins favours the venous current (Ozanam).

From a hydrostatic point of view, the valves are of considerable
importance, as they serve to divide the column of blood into segments
(e.g., in the crural vein in the erect attitude), so that the fine blood-
vessels in the foot are not subjected to the whole amount of the
hydrostatic pressure in the veins.

The velocity of the venous blood has been measured directly (with the hsema-
dromometer and the stromuhr 89). Volkmann found it to be 225 mm. per sec.
in the jugular vein. Reil observed that 24 times more blood flowed from an
arterial orifice than from a venous orifice of the same size. The velocity of the
venous current obviously depends upon the sectional area of the vessel. Borelli
estimated the capacity of the venous system to be 4 times greater than that of the
arterial ; while, according to Haller, the ratio is 9 to 4.

As we proceed from the small veins towards the venae cavae, the
sectional area of the veins, taken as a whole, becomes less, so that the
velocity of the current increases in the same ratio. The velocity of the
current in the venae cavae may be about half of that in the aorta
(Haller).

As the pulmonary veins are narrower than the pulmonary artery,
the blood moves more rapidly in the former. The velocity of the
blood-current in the veins is accelerated during inspiration compare
88 (De Jager).

[Active pulsation occurs in the veins of the wing of the bat (Schiff).]



192 SOUNDS WITHIN ARTERIES.



97. Sounds or Bruits within Arteries.

These murmurs, sounds, or bruits occur either spontaneously, or are produced
by the application of external pressure, whereby the lumen of the vessel is
diminished. In four-fifths of all healthy men two sounds corresponding in
duration and other characters to the two heart-sounds are heard in the carotid
(Conrad, Weil). Sometimes only the second heart-sound is distinguishable, as its
place of origin is near to the carotid. They are not true arterial sounds, but are
simply "propagated heart-sounds."

Arterial Sounds or murmurs are readily produced by pressing upon
a strong artery e.g., the crural in the inguinal region, so as to leave
only a narrow passage for the blood ("Stenosal murmur"). A fine
blood-stream passes with great rapidity and force through this narrow
part, into a wider portion of the artery lying behind the point of com-
pression. Thus arises the " pressure-stream " (P. Niemeyer), or the
"fluid vein" (" Veine fluide" of Chauveau.) The particles of the fluid
are thrown into rapid oscillation, and undergo vibratory movements,
and by their movement produce the sound within the peripheral
dilated portion of the tube. A sound is produced in the fluid by
pressure (Corrigan, Heynsius). The sounds are not caused by vibra-
tions of the vascular wall, as supposed by Bouillaud.

A murmur of this sort is the "sub-clavicular murmur" (Roser), occasionally
heard during systole in the subclavian artery; it occurs when the two layers of the
pleura adhere to the apex of the lung (especially in tubercular diseases of the
lungs), whereby the subclavian artery undergoes a local constriction due to its
being made tense and slightly curved (Friedreich). This result is indicated in a
diminution or absence of the pulse-wave in the radial artery (Weil).

Arterial murmurs are favoured by (1) Sufficient delicacy and
elasticity of the arterial walls (Th. Weber). (2) Diminished peri-
pheral resistance e.g., an easy outflow of the fluid at the end of the
stream (Kiwisch). (3) Accelerated current in the vascular system
generally. (4) A considerable difference of the pressure in the
narrow and wide portions of the tube (Marey). (5) Large calibre of
the arteries.

It is obvious that arterial murmurs will occur in the human body: (a.) When,
owing to pathological conditions, the arterial tube is dilated at one part, into which
the blood-current is forcibly poured from the normal narrow tube. Dilatations of
this sort are called aneurisms, within which murmurs are generally audible.
(6.) "When pressure is exerted upon an artery e.g., by the pressure of the greatly
enlarged arteries during pregnancy, or by a large tumour pressing upon a large
artery, (c.) A murmur corresponding to each pulse-beat is heard, especially where
two or more large arteries lie together; hence, during pregnancy, we hear the uterine
murmur, or placental bruit, or souffle in the greatly dilated uterine arteries. It is
much less distinct in the umbilical arteries of the cord (umbilical murmurs). Similar
sounds are heard through the thin walls of the head of infants (Fisher, 1833). A
murmur due to the systole of the heart is often heard in the carotid (Jurasz). In such



VENOUS MURMURS. 193

cases where no source of external pressure is discoverable, and when no aneurism
is present, the spontaneously occurring sounds are favoured, when at the moment
of arterial rest (cardiac systole) the arterial walls are distended to the slightest
extent, and when during the movement of the pulse (cardiac diastole) the tension
is most rapid (Traube, Weil) i.e., when the low systolic minimum tension of the
arterial wall passes rapidly into the high maximum tension. This is especially the
case in insufficiency of the aortic valves, in which case the sounds in the arteries
are audible over a wide area. If the minimum tension of the arterial wall is
relatively great, even during diastole, the sounds in the arteries are greatly
diminished.

In insufficiency of the aortic valves, characteristic sounds may be heard in the
crural artery. If pressure be exerted upon the artery, a double blowing murmur is
heard; the first one is due to a large mass of blood being propelled into the artery
synchronously with the heart-beat, the second to the fact that a large quantity of
blood flows back into the heart during diastole (Duroziez, 1861). If no pressure
be exercised two sounds are heard, and these seem to be due to a wave propagated
into the arteries by the auricles and ventricles respectively (Landois) compare
73, Fig. 62, III. In atheroma a double sound may sometimes be heard ( 73, 2).

98. Venous Murmurs.

I. Bruit de Diable. This sound is heard above the clavicles in the
furrow between the two heads of the sterno-mastoid, most frequently
on the right side, and in 40 per cent, of all persons examined. It is
either a continuous or a rhythmical murmur, occurring during the
diastole of the heart or during inspiration; it has a whistling or
rushing character, or even a musical quality, and arises within the
bulb of the common jugular vein. When this sound is heard without
pressure being exerted by the stethoscope, it is a pathological phe-
nomenon. If, however, pressure be exerted, and if, at the same time,
the person examined turns his head to the opposite side a similar
sound is heard in nearly all cases (Weil). The pathological bruit de
diable occurs especially in anaemic persons, in lead-poisoning, syphilitic
and scrofulous persons, sometimes in young persons, and less frequently
in elderly people. Sometimes a thrill of the vascular wall may be felt.

Causes. It is due to the vibration of the blood flowing in from the
relatively narrow part of the common jugular vein into the wide
bulbous portion of the vessel, and seems to occur chiefly when the
walls of a thin part of the vein lie close to each other, so that the
current must purl through it. It is clear that pressure from without,
or lateral pressure, as by turning the head to the opposite side, must
favour its occurrence. Its intensity will be increased when the velocity
of the stream is increased, hence inspiration and the diastolic action
of the heart (both of which assist the venous current) increase it. The
erect attitude acts in a similar manner. A similar bruit is sometimes,
though rarely, heard in the subclavian, axillary, thyroid (scrofula), facial,
innominate and crural veins and superior cava.

13



194 THE VENOUS PULSE.

II. Regurgitant Murmurs. On making a sudden effort, a murmur may be
heard in the crural vein during expiration, which is caused by a centrifugal current
of blood, owing to the incompetence or absence of the valves in this region. If the
valves at the jugular bulb are not tight, there may be a bruit with expiration (ex-
piratory jugular vein bruit Hamernjk), or during the cardiac systole (systolic
jugular vein bruit v. Bamberger).

III. Valvular Sounds in Veins. When the tricuspid valve is incompetent,
during the ventricular systole, a large volume of blood is propelled backwards into
the venae cavas. The venous valves are closed suddenly thereby and a sound pro-
duced. This occurs at the bulb or dilatation on the jugular vein (v. Bamberger),
and in the crural vein at the groin (N. Friedreich), i.e., only as long as the valves
are competent. Forced expiration may cause a valvular sound in the crural vein.
No sound is heard in the veins under perfectly normal circumstances.



99. The Venous Pulse Phlebogram.

Methods. A tracing of the movements of a vein, taken with a lightly weighted
sphygmograph, has a characteristic form and is called a phlebogram (Fig. 86). In
order to interpret the various events of the phlebogram it is most important to
record simultaneously the events that take place in the heart. The auricular con-
traction (compare Fig. 29, p. 88), is synchronous with ab; be, with the ven-
tricular systole, during which time the first sound occurs, whilst a, b is a
presystolic movement. The carotid pulse coincides nearly with the apex of the
cardiogram, i.e., almost simultaneously with the descending limb of the phlebogram
(Riegel).

Occasionally in healthy individuals a pulsatile movement, synchronous
with the action of the heart, may be observed in the common jugular
vein. It is either confined to the lower part of the vein, the so-
called bulb, or extends farther up along the trunk of the vein. In
the latter case, the valves above the bulb are insufficient, which is by no
means rare, even in health. The wave-motion passes from below up-
wards, and is most obvious when the person is in the passive horizontal
position, and it is more frequent on the right side, because the right
vein lies nearer the heart than the left.

The venous pulse resembles very closely the tracing of the cardiac
impulse (Landois). Compare Fig. 86, 1, with Fig. 25a, A, p. 82.

It is obvious that, as the jugular vein is in direct communication
with the right auricle, and as the pressure within it is low, the systole of
the right auricle must cause a positive wave to be propagated towards
the peripheral end of the jugular vein. Fig. 86, 9 and 10, are venous
pulses of a healthy person with insufficiency of the valves of the jugular
vein. In these curves, the part a, b, corresponds to the contraction of
the auricle. Occasionally this part consists of two elevations, corre-
sponding to the contraction of the atrium and auricle respectively. As
the blood in the right auricle receives an impulse from the sudden
tension of the tricuspid valve, isochronous with the systole of the right
ventricle, there is a positive wave in the jugular vein in Fig. 86, 9 and



THE VENOUS PULSE.



195



10. indicated by b, c. Lastly, the sudden closure of the pulmonary
valves may even be indicated (g). As the aorta lies in direct relation
with the pulmonary artery, the sudden closure of its valves may also be
indicated (Fig. 86, 9, at d). During the diastole of the auricle and
ventricle, blood flows into the heart, so that the vein partly collapses
and the lever of the recording instrument descends (Riegel, Fran^ois-
Franck).

The blood in the sinuses of the brain also undergoes a pulsatile movement, owing
to the fact that during cardiac diastole much blood flows into the veins (Mosso).
Under favourable circumstances, this movement may be propagated into the veins
of the retina, constituting the venous retinal pulse of the older observers (Helfrich).

Jugular Vein Pulse. The venous pulse in the jugular vein is far better
marked in insufficiency of the tricuspid valve, and the vein may pulsate violently,
but if its valves be perfect the pulse is not propagated along the vein, so that a
pulse in the jugular vein is not necessarily a sign of insufficiency of the tricuspid valve,
but only of insufficiency of the valve of the jugular vein (Friedreich).

Liver Pulse, The ventricular systole is propagated into the valve-less




Fig. 86.



Various forms of venous pulses, chiefly after Friedreich 1-8 from insufficiency of
the tricuspid ; 9 and 10, pulse of the jugular vein of a healthy person. In all
the curves, a, 6= contraction of the right auricle; b, c, of the right ventricle ;
d, closure of the aortic valves ; e, closure of the pulmonary valves ; e, f,
diastole of the right ventricle.

inferior vena cava, and causes the liver pulse. With each systole blood passes into
the hepatic veins, so that the liver undergoes a systolic swelling and injection.



196 DISTRIBUTION OF THE BLOOD.

Fig. 86, 2-8, are curves of the pulse in the common jugular vein (after Friedreich).
Although at first sight the curves appear to be very different, they all agree in this,
that the various events occurring in the heart during a cardiac revolution are
indicated more or less completely. In all the curves, a, b = auricular contraction.
The auricle, when it contracts, excites a positive wave in the veins (Gendrin, 1843,
Marey, Friedreich). The elevation, b, c, is caused by the large blood-wave
produced in the veins, owing to the emptying of the ventricle. It is always greater,
of course, in insufficiency of the tricuspid valves than under normal circumstances
(Fig. 86, 9 and 10). In the latter case, the closure of the tricuspid valve causes only
a slight wave-motion in the auricle. The apex, c, of this wave may be higher or
lower, according to the tension in the vein and the pressure exerted by the spbygmo-
graph. As a general rule, at least one notch (4, 5, 6, e) follows the apex, due to
the prompt closure of the valves of the pulmonary artery. The closure of the
closely adjacent aortic valves may cause a small secondary wave near to e (as in 1
and 2, d). The curve falls towards/, corresponding to the diastole of the heart.

A well-marked venous pulse occurs when the right auricle is greatly
congested, as in cases of insufficiency of the mitral valve or stenosis of
the same orifice. In rare cases, in addition to the pulse in the common
jugular vein, the external jugular, the facial, thyroid, external thoracic
veins, or even the veins of the upper and lower extremities may
pulsate.

A similar pulsation must occur in the pulmonary veins in mitral
insufficiency, but of course the result is not visible.

On rare occasions, a pulse occurs in the veins on the back of the
hand and foot, owing to the arterial pulse being propagated through the
capillaries into the veins. This may occur under normal circumstances,
when the peripheral ends of the arteries become dilated and relaxed
(Quincke), or when the blood-pressure within these vessels rises rapidly
and falls as suddenly, as in insufficiency of the aortic valves.

In progressive effusion into the pericardium, at first the carotid pulse becomes
smaller and the venous pulse larger; beyond a certain pressure, the latter ceases
(Riegel).

100. Distribution of the Blood.

Methods. The methods adopted do not give exact results. J. Ranke ligatured
the parts during life, removed them, and investigated the amount of blood while
the tissues were still warm.

In a rabbit, one-fourth of the total amount of the blood is found in
each of the following : a, in the passive muscles ; 1), in the liver ; c, in
the organs of the circulation (heart and great vessels) ; d, in all other
parts together (J. Ranke).

The amount of blood is influenced by (1) The anatomical distribution (vascularity
or the reverse) of the vessels as a whole ; (2) the diameter of the vessels, which
depends upon physiological causes (a) on the blood-pressure within the vessels ;
(6) on the condition of the vaso-motor or vaso-dilatator nerves ; (c) on the condition
of the tissues themselves, e.g., the vessels of the intestine during absorption; by the
vessels of muscle during muscular contraction ; of vessels in inflamed parts.



PLETHYSMOGRAPHY. 197

Activity of an Organ. The most important factor, however, is the
state of activity of the organ itself; hence, the saying, "ubi irritatio, ibi
affluxus." We may instance the congestion of the salivary glands
and the gastric mucous membrane during digestion, and the increased
vascularity of muscles during contraction. As the activity of organs
varies at different times, the amount of blood in the part or organ goes
hand-in-hand with the variations in its states of activity (J. Eanke).
When some organs are congested others are at rest; during digestion,
there is muscular relaxation and less mental activity : violent muscular
exertion retards digestion during great congestion of the cutaneous
vessels the activity of the kidneys diminishes. Many organs (heart,
muscles of respiration, certain nerve-centres) seem always to be in a
uniform state of activity and vascularity.

During the activity of an organ, the amount of blood in it may be
increased 30 per cent., nay even 47 per cent. The motor organs of
young muscular persons are relatively more vascular than those of old
and feeble persons (J. Eanke).

During a condition of mental activity, the carotid is dilated, the dicrotic wave
in the carotid curve is increased (the radial shows the opposite condition), and the
pulse is increased in frequency (Gley).

In the condition of increased activity, a more rapid renewal of the
blood seems to occur; after muscular exertion the duration of the cir-
culation diminishes (Vierordt).

Age. The development of the heart and large vessels determines a different dis-
tribution of the blood in the child from that which obtains in the adult. The heart is
relatively small from infancy up to puberty, the vessels are relatively large ; while
after puberty the heart is large, and the vessels are relatively smaller. Hence, it
follows that the blood-pressure in the arteries of the systemic circulation must be
lower in the child than in the adult. The pulmonary artery is relatively wide in
the child, while the aorta is relatively small ; after puberty both vessels have
nearly the same size. Hence, it follows that the blood-pressure in the pulmonary
vessels of the child is relatively higher than that in the adult (Beneke).



101. Plethysmography.

Plethysmograph. In order to estimate and register the amount of
blood in a limb Mosso devised an instrument (Fig. 87), which he
termed a Plethysmograph. It is constructed on the same principle as
the less perfect apparatus of Chelius and Fick.

It consists of a long cylindrical glass- vessel, G, suited to accommodate a limb.
The opening through which the limb is introduced is closed with caoutchouc, and
the vessel is filled with water. There is an opening in the side of the vessel in
which a manometer tube, filled to a certain height with water, is fixed. As the
arm is enlarged with the increased supply of arterial blood passing into it at each