396 Animal Biology 



tubular aorta (Gr. aorta, the great artery) extends anteriorly from the 

 heart and opens into the body cavity known as a hemocoel in the region 

 of the head. The hemocoel contains the internal organs and circulates 

 the colorless blood. This so-called "open system" of circulation causes 

 the blood to flow in vessels only part of the time; most of the time it 

 flows in tissue spaces or sinuses in the body and appendages. The blood 



Hearts Alalpiqhian tubes 



Rectum 



--Anus 



^ Pharynx SaVw/ary Qastric Stomach Irttest'ine 



c^land caeca 



Oviduct 

 i 



Cement gland 

 / 



\ ^ 1 



Id Suhesophacjeal qanqJion AbdorninaJ aanqlion 



(jenital opening 



Trachea 

 / 

 / 



Air sac 



Spiracle 



Fig. 



193. — Internal anatomy of the grasshopper. A, Digestive and circulatory 

 systems; B^ reproductive and nervous systems; C, respiratory system. 



flows from the heart through the aorta into the hemocoel from which 

 the various systems receive nourishment. Eventually the blood returns 

 to the pericardial sinus. The liquid plasma of the blood contains color- 

 less white blood corpuscles or leucocytes (lu'kosite) (Gr. leukos, white; 

 kytosj hollow or "cell"). 



