TYPE PROTOCHORDATA. 



629 



and it is probable that it is aii aggregation of forms with quite 

 distinct derivations. The varieties of budding which are 

 found are quite numerous. In some cases it closely resem- 

 bles that of Clavellina, some species of Distaplia, for example, 

 possessing a short stolon, essentially similar to that of the 

 former genus, from which buds arise which, however, early 

 separate from the stolon and remain imbedded in the thick 



FIG. 287. A, YOUNG SOLITARY Amarwcium DEVELOPED FROM EGG ; B, A 

 SLIGHTLY ULDEK FORM, IN WHICH THE POSTABDOMEN is SEGMENTED ; C, 



THE NON-SEXUALLY PRODUCED FoRMS MIGRATING TOWARDS THE SURFACE 

 OF THE TEST (after KOWALEWSKY from KORSCHELT and HEIDEE). 

 a = parent individual. b = bud which has reached the surface. 



c migrating buds. 



test of the parent, a repetition of this process through several 

 generations leading to the formation of massive colonies. 



In Amarcecium the arrangement is a little different, but can 

 readily be traced back to the stolon form. The posterior eud 

 of the body in budding forms is continued backwards as a 

 long postabdomen (Fig. 287, A), having a structure similar to 

 the stolon of Clavellina, but instead of giving off buds the 

 stolon segments into a number of parts (Fig. 287, B) which, 



