126 PRACTICAL ZOOLOGY. 



white membrane and the body of the kidney. Note 

 the branches of this cavity into the kidney. Note 

 also the extension of the white membrane into these 

 cavities. Make out that the blood-vessels extend 

 through these white branches to the outer parts of 

 the kidney. Count these branches. 



4. In the center of the white membrane find the opening 

 of the ureter, through which the urine is conveyed to 

 the bladder. Pass a probe through this opening into 

 the ureter. 



5. Note the difference in color of the outer and inner 

 parts of the kidney. At the line of change of color 

 find where the blood-vessels first branch into the real 

 kidney substance. Examine carefully the cut surface 

 of the kidney to see its markings. 



6. Make a drawing of one-half of the kidney as seen 

 from the inside, showing all the above-named points. 



7. Cut across the middle of the kidney at right angles to 

 its length, and make a drawing of this cross-section. 

 The projection of the kidney substance into the cavity 

 opposite the ureter is the urinary pyramid, and from 

 its apex, through many fine holes, issues the urine 

 which the kidney has secreted from the blood. 



THE BRAIN AND SPINAL CORD. 



1. Slit the skin along the middle of the back from the 

 nose to the tail, and strip it back well to the sides. 

 Dissect away the muscles from the back of the head 

 and the fore part of the neck ; between the skull and 

 the first vertebra, or atlas, is a space covered by a 

 thin membrane, through which the white spinal cord 



