In studying the diseases of the, kidneys, it is necessary to bear constantly in mind the general facts as to their structure, otherwise the examination of the organs will lead to confusion. The functions of the kidney must also be understood in their outlines in order to a comprehension of the changes wrought by disease.

The normal kidney measures about 4 inches in length, 2 1/2 in breadth, and 1 1/2 in thickness. The weight varies considerably, the average for the male being 4 1/2 to 5 ounces, and for the female slightly less. The surface is smooth and the capsule although closely applied to the surface can be readily stripped off. On section the tissue is seen to be very regular, the distinction of pyramids and cortex being well defined.