63 



to get a froth, when the sulphuric acid is added the froth 

 shows the color. 



Blood in the urine (Hematuria), pus and other organic 

 deposits in the urine require microscopic analysis. 



XXII. 



287. Place a frog on its belly and note the movements of 

 the caudal lymph-hearts. They are situated between the 

 hip-joint and the median line in a slight depression. The 

 contractions of these hearts are usually visible through the 

 skin, but are seen more distinctly if the skin is removed 

 without injury to the hearts. 



Later, note that the lymph-hearts cease to beat after the 

 destruction of the caudal portion of the myel (spinal cord). 



288. Pith the frog. This is accomplished by severing the 

 brain from the myel with a thin bladed knife at the point 

 where the cranium articulates with the atlas. A slight de- 

 pression will be felt at this point, which will serve as a guide 

 for the operation. The frog may be firmly held if wrapped 

 in one corner of a towel. 



289. After pithing, lay the frog on its back, and cut 

 through the .skin on the mid-line, and from the middle of 

 this cut make lateral incisions through the skin. Raise up 

 the end of the sternum and cut, a little to one side of the 

 mid-line, through such parts as may be necessary to expose 

 the heart. Pin the parts out, on the side and note the heart 

 beating with some force and regularity. Pinch up the peri- 

 cardium with a pair of fine forceps and remove it from the 

 heart. Tilt up the apex of the ventricle and note a small 

 band of connective tissue passing from its dorsal surface to 

 the adjoining wall of the pericardium^* Seize this band with 

 the forceps and divide it between the forceps and the peri- 

 cardial wall. Lift up the apex of the ventricle, by means of 



