142 



BOYS AND GIRLS IN BIOLOGY. 



ceives the waste fluids and carbonic acid. Now the 

 blood must be taken to the gills to be purified, and so 

 it is collected from the hair-tubes (capillaries) by the 



Fig. 123. 



Ventricle 



Valve 



Artery, 



Heart and its Vessels. 



veins, which carry it to the blood-chambers in the 

 breast, or thorax. The blood-chambers then send the 

 blood to the gills, where it is distributed and aerated, 

 or purified, through the fine net-work of the gills. 

 From the gills it is carried by vessels into the heart- 



