inal pressure consists of two factors, viz.: (a) the most important is that due to muscular tension; (b) that due to atmospheric pressure.

Intra-abdominal pressure is of two kinds, viz.: Positive and negative. Positive muscular pressure is where the resting condition, a viscus, receives support as the ureter lying on the psoas, the internal genitals lying on the levator ani (pelvic floor) or the enteron loops lying against the ventral abdominal wall. Negative muscular pressure is where the viscera are retained in position indirectly, i. e., if the viscus attempts to leave its normal postion the muscular pressure prevents it.

To the causes of greater or less mobility of the kidney we must look to, 1, the length of the arteria renalis; 2, intra-abdominal pressure; 3, to the syntopic relations of the kidney in other wards to the visceral fixation apparatus of the calyces and pelvis, i. e., to pressure and counter-pressure. In the syntopic relations of the kidney the three visceral factors playing the chief role are: (a) the paniculus adiposa; (b) the verticle cola; (c) the peritoneum.

The degree of mobility of the calyces and pelvis (kidney) has received different opinions from different observers. Does the kidney share in the active and passive corporeal movements? In the passive corporeal movements of the body the kidney has the following motions, viz.: (a) expansion (rhythm); (b) contraction (rhythm); (c) positional translation from force of gravity, as distalward, proximalward and ventral ward movements. In active (muscular) corporeal movements the calyces and pelvis. have the following motions, viz.: (a) ventralward, especially in the proximal end of the calyces from the pillars of the diaphragm; (b) distalward from the diaphragm in respiration. The motion of the kidney from the diaphragm in normal respiration is slight, but palpable in strong respiration. The movements of calyces and pelvis by respiratory action of the diaphragm is physiological. The liver moves the calyces and pelvis by means of the diaphragm. The direction of the movements of the calyces and pelvis is conditional through the fixation apparatus and the normal position. The motions are practically constant.

Since the origin of the right vascular pedicle (vasa renalis) is fixed at the level of the I lumbar vertebra, the segment of the circle through which the right kidney can move is defined by the length of the vena renalis as a radius inserted into the vena cava inferior, while the segment of the circle through which the renis sinistra moves is defined by the arteria renalis sinistra as a radius inserted in the aorta abdominalis. From my observations in over 500 autopsic abdominal inspections with especial regard to splanchnoptosia, I am convinced that in nephroptosia (as in other splanchnoptosis) the vasa renalis experiences elongation, and that a direct distalward movement of the kidney occur without the usual normal bilateral approach of the distal calyces and pelvis in the middle corporeal line.

If the kidney in the normal condition, e. g., normal length of vasa renalis pass distal ward the distal renal pole must approach nearer the middle line. We have noted above the differences of the various fixation apparatus of the right and left kidneys, as (a) the length of the bilateral vasa renalis; (b) the intra-abdominal pressure (muscular, atmospheric action);

(c) the visceral pressure and counter-pressure; (d) right and left colon; (e) the peritoneum; (f) the paniculus adiposa renalis; (g) the perirenal fascia; (h) the differences of size in the right and left renal bed, and that the right kidney experience more mobility than the left. However, if one opens numerous cadavers, carefully palpates and testing the mobility of

FIG. 2 is an illustration to show Renal Anteversion, the evident cause of suffering in many cases of nephroptosia. 1, shows the kidney lying on the dorsal abdominal wall. 2, shows the anteverted kidney. 3, the ureteral pelvis. 4, the proximal isthmus. 5, lumbar spindle of ureter. 6, middle ureteral isthmus. 7, the vasa spermatica. The cut is drawn rather too much with a ventral view, and not enough in profile view to present a typical renal anteversion.

right and left kidney, it will be found that the right kidney is about 10 per cent, only more mobile than the left, while perhaps in 5 per cent the left kidney is more mobile than the right. Again, perhaps, in 50 per cent of subjects the right and left (kidney) are equal in mobility.

It must be remembered that this cadaver testing of renal mobility is in two directions only, viz.: Proximalward and distalward. This test method does not include the most important of all renal motions, viz., ventralward movements (renal anteversion). I have noted many cadavers in which the renal translation movement was 1 proximalward and 13 inches distalward. The average proximalward and distalward translation renal movements found in several hundred cadavers were one inch proximalward and one inch distalward. The average shiftability or mobility of the kidney is a verticle range, two inches.

The right kidney finds the more free movements distalward on account of the liver and long arteria renalis, while the left find the more free movements proximalward, as the spleen does not obstruct the left renal motion to any great extent. However, the right kidney has a wider proximalward range than the left when it glides dorsal to the liver, and such cases are not rare. Hence the chief question in ureteral surgery as regards position is the capacity of distalward movements of the right kidney over that of the left. The important question is which kidney has the freer distal ward movement. It must be answered that it is that of the right side.

The dorso-ventral movements of the kidney is all ventralward as the dorsal wall is fixed and will not yield. In cadavers one can make partial tests only of the ventralward movements of the kidney. The ventral ward movements are best tested in the living, spare, erect patient. The proximal end of the right kidney is located more ventralward than that of the left. The proximal end of the right kidney is inclined more ventralward than that of the left. If one opens the abdomen from the dorsal side the left kidney will appear directly in view while the right side will be mainly covered by the transverse processes of the lumbar vertebrae. The right kidney is shorter longitudinally than the left, and hence easier dislocated.

The degree of mobility of the kidney is remarkably various. The zone of mobility extends from zero (fixation) to three inches in the proximo-distal line. The dorso-ventral zone of renal mobility, though perhaps the most important clinically, surgically, is the most difficult of measurements. Perhaps it may reach two inches. Seventy per cent of multipara (and almost a simliar number of nullipara) possess mobile kidney. My experience with men are more limited, but should judge that 50 per cent of men over 30 years of age have mobile kidney. Splanchnopt osia increases steadily after 30 years of age, hence nephroptosia perhaps increases in direct proportion. In woman there is age and functional relations as regards nephroptosia. The ureter experiences age and functional relations. on account of the arteria uterina ovarica emitting the proximal and distal arteria ureterica. During the congestion and decongestions of the uteroovarian artery the ureter shares the variations in blood stream. A rapid disappearance of the paniculus adiposus renalis is a fruitful cause of nephroptosia in either sex.

Here may be discussed excessively, mobile kidney. What is a pathologic mobile kidney? An excessively mobile kidney apparatus comes under the designation of wandering or floating kidney, or better, nephroptosia.

Nephroptosia includes three views.: 1, a kidney with a mesonephron -an elongated peritoneal duplicature which is congenital and allows the

FIG. 1 illustrates nephroptosia dextra. 1, the nephrotic kidney. 2, the elongated renal artery. 3. the flexed aud dislocated ureter. The left kidney and ureter is represented as normal. A and B represent the apex of the ureters-venous triangles, the right being especially distorted by nephroptosia. Right nephroptosia in man is due to the erect attitude, as in dog, pig, cow, horse the right kidney lies proximal to the the left, obeying the law of gravity. It is common in autopsy for a kidney to move distalward 11⁄2 inches and proximalward 11⁄2 inches-a range of 3 inches, yet the subject never complained of nephroptosia while living. Nephroptosia requires operation only when it give rise to pathologic symptoms.

kidney to become an evaginated loose floating viscus, practically within the cavum peritonei. I never saw one in surgical intervention, nor in witnessing numerous autopsies.

The nephroptosia includes the idea that a kidney from relaxed abdominal wall and elongated fixation renal apparatus moves excessively freely in

the abdominal cavity, is distinctly palpable. The nephroptosia comprehends the view of clinical symptoms complex in which the role of dragging sensation, pain in the anterior crural and genito crural nerves, gastric crises, relief of symptoms by assuming the horizontal position, constipation and finally various degrees of neurosis. It is difficult to draw the line between a normally mobile kidney and a pathologic mobile one, except through clinical symptoms complex. For in nephroptosia in the cadaver the kidney assumes the normal renal bed. A kidney with a mesonephron is pathologic rara avis. The blood stream from the arteria uterina ovarica, as in climacterium and senescence will produce a rapid disappearance of the blood current in the arteria ureterica proximal, hence the lack of nourishment in its lumbar spindle produces lack of nourishment and irregular dilatations in the lumbar ureter. The forces which produce excessively mobile kidney require a continuous action. If the diaphragm has a distalward situation it is liable to exercise a continuous force on its kidney. Again, in enlargement of the spleen and liver the diaphragm through them is liable to force the kidney distalward. Besides the dislocation of the uretero-venous triangles, the congestion and decongestionending in renal parenchymatous impairment, nephritis. In infants with relatively larger liver the right kidney assume a more distalward position than in adults. In atrophic liver the right kidney is liable to be on the same level as the left.

Deviation of the liver and spleen from the usual position is in my opinion most intimately related to relaxed and irregular activity of the abdominal walls-diaphragm and ventral walls.

The volume increase of the liver induces a distal ward movement of the right calyces and pelvis. In fact at autopsies one can note that enlarged livers force the right kidney into various positions so that sometimes the hilus renalis may present proximalward. These various distortions of the kidney by enlarged liver disturbs its rhythmical mechanism, obstructs the flow of urine, inducing urinal deposits which furnish bacterial media, ending in calculi. This is of course the pressure from the thoracic cavity through the diaphragm as an intermediary on the liver, spleen, stomach, etc. The extreme positions of the diaphragm doubtless influences the position of the kidney.

The immediately adjacent organs of influence on the position of the kidney are especially the liver and spleen. The liver tumors will in general displace the kidney distalward only when the tumor sits on the dorsal surface of the liver proximal to the proximal pole of the kidney, whence by its growth it forces the calyces and pelvis distalward. Enlargements of the spleen doubtless can force the left calyces and pelvis distalward.

In regard to atrophy of the spleen influencing the position I can make no statements. The stomach has little influence on the position of the right or left kidney, because, 1st, its rest on the ventral renal surface only; 2d, its enlarged full condition lasts but a short time. Numerous tumors may dislocate the kidney besides pathologic deformities of the skeleton will distort the position of the kidney which exceeds the purpose of this investigation.