248 STUDIES IN PHYSIOLOGY 



4. A STUDY OF THE SHEEP KIDNEY* 



General Appearance of the Kidney. One can secure of any 

 butcher the kidney of a sheep. It is inclosed in a mass 

 of fat. On pulling this away, one finds a thin membrane 

 of connective tissue which closely envelops the kidney. 

 When this covering is opened, there appears a dark red 

 organ, more or less elliptical in outline. It is somewhat 

 flattened, too, and is hollowed in on one edge, in fact, it 

 has almost the exact shape of a bean seed. From the region 

 of the hollow or hi'lum of the kidney passes out a tube 

 called the u-re'ter (compare with Fig. 113). Large blood 

 vessels also enter and leave the kidney in this region. 



Longitudinal Section of the Kidney. If one divides this 

 organ in halves by cutting through from its convex edge to 

 the hilum, one can make out pretty clearly the internal 

 structure. At the hilum the ureter expands into a consider- 

 able cavity called the pel'vis of the kidney. Around this 

 cavity the kidney is seen to be divided into two distinct re- 

 gions. The outer or cor'ti-cal (Latin cortex = bark) has a 

 dark brownish red color and is granular in appearance. 

 The inner or med'ul-la-ry layer is made up of cone-shaped 

 masses, and the apex of each of these pyramids projects into 

 the pelvis of the kidney. The general appearance of the 

 medullary layer is red and glistening. Fine lines run 

 through the pyramids from base to apex. 



5. ANATOMY AND PHYSIOLOGY OF THE HUMAN KIDNEY 



Position and Appearance. In shape and general appear- 

 ance human kidneys resemble closely these organs of a 

 sheep. The two kidneys are attached to the dorsal part of 

 the cavity of the abdomen in the region of the loins, and 

 the ureters come off from the median border of each. In the 

 longitudinal section the pyramids of the medullary layer 

 are seen much more distinctly, however, than in the sheep 



iSee "Laboratory Exercises," No. 44. 



