184 



PRACTICAL ZOOLOGY 



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

 internal organs are 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 h /■>, h) 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 



atworm. 



en, brain ; e, eye ; g, ovary ; ii, i 2 , i3, 

 branches of intestine; In, lateral 

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

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

 glands; vd, vas deferens; d", penis; 

 ?, vagina; cf ? , common genital pore. 

 (After V. Graff.) 



