MULTICELLULAR ANIMALS 



185 



contact between these structures and the coelomic fluid. The nephrid- 

 ial tubules pass forward and open out through the ventral body 

 wall of the next anterior segment. In Crustacea, the lobster and its 

 allies, a pair of green glands (Fig. 127) located at the bases of the 



v>-> 



ROSTRUM 



EYE 



ANTENNULE 



ANTENNA 



EXCRETORY RORE 



GREEN GLAND 



Fi« 127. — The green gland, excretory organs of a lobster. 



antennae abstract the non-gaseous wastes from the circulation and 

 expel them. In insects a series of fine malpighian tubules are found 

 in the body cavity (Fig. 128). These tubes open into the intestine, 



MALPIGHIAN TUBULE 

 INTESTINE 



Fig. 128. — Diagram representing the Malpighian tubules, the excretory organs of 

 an insect, and their position. (After Kiihn: Grimdriss der allgemeinen Zoologie. 

 Georg Theime, Leipzig.) 



into which the wastes from metabolism are collected together with 

 the farcal materials, and expelled. It may be remarked that this 

 close association between excretory system and digestive system is 

 unusual; in general, the two systems are widely separated and have 



