184 



PRACTICAL ZOOLOGY 



Because of the great amount of coloring matter in its body the 

 internal organs aje difficult to make out. They may be de- 

 scribed briefly with the aid of 

 a diagram (Fig. 105). A mus- 

 cular pharynx can be extended 

 from the mouth as a proboscis 

 (Fig. 104, j) ; this facilitates 

 the capture of food. The food 

 is digested in the intestinal 

 trunks (Fig. 105, i lt i 2 , / 3 ) by se- 

 cretions from their walls and is 

 absorbed by the walls. Since 

 branches from these penetrate 

 all parts of the body, no circu- 

 latory system is necessary to 

 carry nutriment from one place 

 to another. The excretory 

 matter is collected and carried 

 to the outside by a pair of longi- 

 tudinal, much-coiled tubes, one 

 on each side of the body; these 

 are connected near the anterior 

 end by a transverse tube, and 

 then open to the exterior in 

 two small pores on the dorsal 

 surface. 



Planaria possesses a well-de- 

 veloped nervous system, con- 

 sisting of a bilobed mass just 

 beneath the eyespots called the 

 brain (Fig. 105, en), and two 

 lateral longitudinal nerve cords 

 (In), connected by transverse 

 nerves. From the brain, nerves pass to various parts of the 

 anterior end of the body, imparting to this region a highly 



FIG. 105. Anatomy of a flatworm. 



en, brain ; e, eye ; g, ovary ; ii, i 2 , is, 

 branches of intestine; In, lateral 

 nerve; m, mouth; od, oviduct; ph, 

 pharynx; t, testis; u, uterus; v, yolk 

 glands; vd, vas deferens; cf, penis; 

 ?, vagina; d 1 ?, common genital pore. 

 (After V. Graff.) 



