ze 
the displacement towards the pelvis; and are also unable to prevent 
the normal forward migration of the organ, as shown in cases where 
the definitive renal vessels have been found to arise as far caudally 
as the level of the A. mesenterica inferior, with normal position of 
the kidneys. 
It is also possible for the kidney to become displaced where it 
does not push into the body-cavity to the extent just mentioned, but 
remains partially retroperitoneal. Such an organ eventually becomes 
fixed and forms a type of kidney situated at a greater or less distance 
caudad of the normal position, with blood-vessels arising at the 
usual level. 
The causes producing the abnormal protrusion of the kidneys 
into the body-cavity are obscure, though they may probably be referred 
to processes of growth in adjacent organs, which are essentially normal 
but perhaps exaggerated in one direction or another. SCHOENLANK 
sees in the testis a probable factor in this connection, concerning 
which he says: „Der Hoden liegt ursprünglich der hinteren Bauch- 
wand an, durch ein kurzes Mesogenitale an sie befestigt. Sein kau- 
daler Pol wird dadurch gegen die vordere Bauchwand und damit 
gegen das Ostium inguinale abdominale verschoben, dass sich im Re- 
troperitoneum ein gewaltiges Mesenchympolster entwickelt, welches 
Bauchfell samt Mesogenitale und Hoden ventralwärts drängt. Wenn 
nun ein solcher Vorgang anormalerweise weiter kranialwärts reichen 
würde, so wäre es sehr leicht denkbar, dab er neben dem Hoden 
auch die Niere zu beeinflussen imstande wäre.“ 
The so-called horseshoe kidney results from the fusing together 
of the two kidneys to a greater or less degree. The organs may be 
united merely by a narrow strip of renal substance or connective 
tissue, on the one extreme, while on the other the entire length of 
the kidneys may be involved, the two organs being fused into a single 
compact discoidal mass which is called by German authors ‘‘ Kuchen- 
niere.”’” When a well-defined fusion between the caudal, very rarely 
the cephalic, poles of the kidneys occurs, the typical horseshoe form 
of kidney results. 
A kidney of this type may be displaced to a greater or less degree. 
According to Murumann, when there is fusion of the caudal poles, 
the organ lies typically with its caudal end at the bifurcation of the 
aorta, only a single instance having been recorded where the organ 
lay at the normal level. When the cephalic ends are fused, it may 
