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common variety appears to be that of two on one side and one on the 
other. When more than two arteries are present, the increase is 
generally on the left side. Two, three, and four arteries on one side 
are frequently met with; numbers above that, especially on the right 
side, seem to be less frequent. Orro and Mecxrn (1) record cases of 
five renal arteries on the right side. Kater (4) has recorded a case 
of quintuple arteries on the right side, the most posterior one arising 
however from the right common iliac artery. Young and Tuomson (5) 
in their article on multiple renal arteries, record one case of quintuple 
arteries on the left side, the most posterior in this instance arising from 
the left common iliac artery. In the Collective Investigation Report of 
the Anatomical Society (2) for the year 1889—90, on this subject, of 
the four hundred and ninteen kidneys examined, three were found to 
possess four arteries; no examples of quintuple arteries were found. 
Usually increase in the number of renal arteries is accompanied by 
abnormalities in the kidney itself, in the renal vein, or in the ureter. 
Newman (6), and also SUTHERLAND and Epıngron (7) have described 
numerous cases of abnormal kidneys, accompanied in the majority of 
cases by increase in the number of the arteries. 
Multiple renal arteries are interesting from the point of view of 
morphology. In fishes numerous small arteries, arising from the aorta, 
pass to the elongated kidneys. In fishes the kidney is the mesonephros 
which is a segmental organ and the occurrence of numerous arteries is 
explicable on that account. In reptiles and birds the kidneys usually 
receive several branches from the aorta. But in these animals as well 
as in mammals the kidney is the metanephros which is undoubtedly 
not a segmental organ. Some writers (5) have endeavoured to explain 
the occurrence of multiple renal arteries by supposing that the kidney 
is a segmental organ supplied by segmentally disposed arteries. The 
study of the development of the kidney has shown conclusively that 
the kidney is not a segmental organ so that this theory is not tenable. 
Other anatomists e. g. Testur, R. Quaın, regard multiple renal arteries 
as simply being due to the various branches of the renal artery arising 
sooner than normal, the origin of the branches having travelled in, as 
it were, and come to arise separately from the aorta instead of from 
one common stem. While this may be a feasible explanation of the 
origin of two or three arteries arising close together from the aorta 
and passing into the hilum of the kidney it hardly suffices to explain 
those cases in which the arteries arise at considerable distances from 
each other from the aorta or other vessels and where the relations to 
the vein and ureter are so different from the normal. Rather must 
such cases be regarded as a reversion to the primitive segmental con- 
dition of the bloodvessels. One can still trace segmentation in other 
visceral branches of the aorta, the coeliac axis, the superior and inferior 
mesenteric arteries. The suprarenal, spermatic, and renal arteries may 
be regarded as forming a group somewhat intermediate between the 
visceral and parietal branches, and, owing to the position of the kidney 
and testes in development, they are probably more closely related to 
the parietal than to the visceral group Originally more numerous, they 
