a’ 
terval it contracted again, and slowly and gra- 
dually recovered an action of considerable fre- 
quency and vigour.” 
“ A frog was made perfectly insensible by 
the application of laudanum or alcohol. Its 
respiration ceased. It did not move on the 
application of any irritant. The circulation in 
the web was carefully observed. When it had 
long continued in the same enfeebled state 
without change, the thigh was crushed. The 
circulation in the minute and capillary vessels 
ceased at once, and never returned. The sto- 
mach was now crushed in the same manner. 
The heart ceased to beat for many seconds. 
Its beat then returned, but never regained its 
former force.” 
In these experiments we have the sudden 
influence of shock and its gradual subsidence. 
The experiment is peculiarly interesting in 
many points of view :— 1. it is the only one on 
record of the effects of shock induced solely 
and exclusively through the medium of the 
ganglionic system ; 2. it exemplifies the. effect 
of shock or excessive stimulus on the heart, 
with its gradual though incomplete subsidence. 
The connexion of the ganglionic system with 
the irritability of the visceral muscles,—the 
heart, the stomach, the intestines, &c. forms the 
subject of an experimental investigation, in 
which I am at this moment engaged, and the 
results of which I purpose to give under the 
head of vis nervosa and vis insita. It is pro- 
bable that the ganglia are to thé internal mus- 
cular organs what the spinal marrow is to the 
muscles of the limbs, viz. the power of irritabi- 
lity, &c. This inquiry is founded on a fact 
first ascertained by myself, that, in spring, we 
may, by portions at a time with considerable 
intervals, totally destroy the brain and spinal 
marrow in the frog, eel, &c. leaving the circula- 
tion in the web or the fins and tail.* Wehave 
thus isolated the ganglionic from the rest of the 
nervous system, on which we may therefore 
proceed to experiment, watching the effect of 
various agents on the circulation and on the 
action of the heart, the stomach, the intestines. 
We have thus passed in review in its anato- 
mical, physiological, zoological, pathological, 
and those peculiar relations, the question of the 
irritability of the muscular fibre. It only 
remains for us to advert, once more, to the ex- 
treme importance of this principle in physiology : 
all physiology is involved, indeed, in the topic 
of the nervous system and the vascular system, 
and the principle of irritability seems, with its 
various and appropriate stimuli, to be placed 
between those two. 
(Marshall Hail.) 
JOINT.—See Articutation, and the arti- 
cles under the headings of the several joints for 
both the normal and abnormal anatomy. 
KIDNEY .—See Ren. 
KNEE-JOINT (normal anatomy of the). 
Gr. yév; Lat. genu; Fr. genou; Germ. 
* Op. cit, p. 136, 
NORMAL ANATOMY OF THE KNEE-JOINT. 
. pelvis in women gives, ceteris paribus, — 
Kniegelenk ; Ital. ginocchio. The knee-joi 
the largest joint in the body, results from t 
articulation of the os femoris with the tk 
below and the patella anteriorly. It admits 
extensive motion as a ginglymus, to which 
added an arthrodial motion, or a small degre 
rotation of the leg and foot, when the jon 
partly flexed. The articular surfaces are lai 
and complicated, the ligaments numerous, a 
the joint chiefly superficial; circumstam 
necessary to the freedom, stability, and sy 
metry of the limb, but exposing this import 
articulation to frequent accident and disea 
It is intended here to describe so much of 
the bones entering into the formation oj 
joint, and, 6, the cartilages, ligaments, &e., 
may be necessary to the elucidation of, ¢, | 
mechanical functions. 
(a.) Bones. The shaft of the os femor 
which in the middle of the thigh is triangul: 
becomes of a four-sided form as it approach 
the knee, in consequence of the bifurcatic 
the linea aspera. This rough ridge, whic 
the middle of the bone forms a prominent px 
terior angle, divides on entering its inferior hi 
into two diverging lines which terminate at 
convex articulating eminences called condyle 
a flat triangular surface of bone is thus 
where the popliteal vessels lie. The outer lit 
is most strongly marked, and gives origin to 
vastus externus and short head of the bice 
flexor cruris: the inner line is deficient ne; 
the upper part, over which the femoral 
pass into the ham; it gives attachment bek 
to the vastus internus and adductor magn 
The internal condyle is narrower and more pr 
jecting behind than the external; and in rel 
tion to the shaft of the bone, it appears to exten 
further downwards; but the natural obliqt 
pesition of the os femoris brings the condyh 
nearly horizontal. The greater width of th 
na 
greater obliquity to the os femoris than in m 
The condyles are separated behind by a d 
fossa, out of which the crucial ligaments t 
their origin ; their articulating surfaces are con 
vex both in the transverse and in the anter 
posterior directions, until in front they coales 
into ove pulley-like surface over which — 
patella plays in the motions of the joint: thi 
trochlea is convex from above downwards, br 
concave from side to side ; its outer half is me 
prominent than the inner, and extends high 
up the corresponding condyle. Above th 
trochlea there is a flattened or slightly depres 
surface, upon which the patella partly resi 
during complete extension of the joint, T 
thickness of the os femoris from front to b 
undergoes little change till the condyles sui 
denly jut out behind, and the edges of t 
trochlea rise up in front ; but from side to sid 
the shaft of the bone increases in breadth as: 
approaches the knee, the two postero-late: 
surfaces winding gradually round to beco 
antero-lateral, at the same time diverging ra 
pidly to form a smooth slope on the side of each 
condyle. Towards the posterior part of each 
of these sloping surfaces, there is an irregul 
prominence called the tuberosity, for the attach 
