METABOLIC GRADIENT IN ANNELIDS 



9 



It may be emphasized that these pieces are as nearly ahke 

 morphologically as is possible to obtain in elongated animals. 

 The digestive tract of Lumbriculus is not differentiated except 



4 



-X 



Fig. 2 Lumbriculus inconstans, showing the manner of cutting the three 

 pieces v>'hose oxygen consumption is given in table 1. x indicates zone of 

 autotomy. 



Fig. 3 Nereis virens, showing the manner of cutting the three pieces whose 

 oxygen consumption is given in tables 2 and 3. 



in the head region, where it forms a pharynx; but this, as, already 

 stated, is cut off and discarded. There are no reproductive 

 organs. The circulatory system forms a loop with the sacs charac- 

 teristic of the lumbriculids in each segment. The onlj^ differ- 



