ORGANIZATION AND GROWTH 



essential point is again this, that the place of the new growth 

 is determined by the orientation of the stem toward the cen- 

 ter of the earth, inasmuch as sf<-nis arise only from the ii)>]>er 

 surface, tin- roofs only from Hie loirer surface, of ihe element. 

 That a new stem may arise from the upper surface of any 



FIG. 15 



element of a stem which is put obliquely is evidenced by the 

 fact that such stems arise at times from the upper surface of 

 the lowest elements of the animal. Such a case is shown in 

 Fig. 4-~>. The stem of an Antennularian was bent so that 

 the two ends were directed obliquely downward. New stems, 

 $,, S.,, *S.,, S t , , have formed upon the upper surfaces 

 of different elements of the old stem. ,S, has grown from 



