108 



BOYS AND GIRLS IN BIOLOGY. 



cells which you saw in yours under the microscope. 

 The blood of the mussel is made of water and colorless 

 cells, which move about quite like the human amceb^e. 

 Below the heart-sac, or pericardium, lie the kidneys: 

 they are also called the organs of Bojanus, from the 

 name of their discoverer. They have two chambers, an 

 upper and a lower (Fig. 101). The upper one is clear 



Fig. 101. 

 Door from Lower Kidney— leading 



Upper Part of 

 Kidney. 



Lower Part of 

 Kidney. 



Door from Upper Kidney into Front- 

 Room, or Ventral Chamber. 



and transparent, and has a door which opens into the 

 mussel's big room, or ventral chamber (Fig. 101). 

 The lower chamber of the kidney is of a dark, choco- 

 late color, and it has a door which opens into the heart- 

 bag, or pericardium (Fig. 101). It is in the dark, under 

 part, where the blood which runs through the kidney is 

 made pure (Fig. 102). Around the stomach lies a 

 dark-brown-looking mass, and this is the liver. It 

 makes or manufactures bile, and pours it into the stom- 



