FORM REGULATION IN CERIANTHUS. 



30/ 



B. One piece beginning to fill with water ; others collapsed. 



C. One piece beginning to fill ; others collapsed. 



D. All collapsed. 



November i 2 : Five days after section : 



A. Marginal tentacular ridge distinct, with fading pigment. 



B. All distended ; new tissue at ends visible ; ten- 

 tacular ridge forming. 



C. One piece distended ; new tissue at ends visible ; 

 two pieces partly filled but not sufficiently to show 

 the new tissue at the ends ; one piece still col- 

 lapsed. 



D. All still collapsed. 



November 1 5 : Eight days after section : 



A. Marginal tentacles just appearing in all. 



B. One piece with marginal tentacles just appear- 

 ing ; three pieces distended ; new tissue at ends visible ; 

 tentacular ridge distinct, unpigmented. 



C. Two pieces distended ; new tissue at ends visi- 

 ble; tentacular ridge forming ; one piece still col- 

 lapsed ; one piece collapsed and completely enclosed 

 in slime which was removed. 1 



D. All still collapsed. 



November 20 : Thirteen days after section : 



A. Marginal tentacles in all I mm. in length. 



B. In one piece marginal tentacles i mm., in others about 

 0.5 mm. 



C. All distended ; tentacular ridge unpigmented, marginal 

 tentacles just appearing. 



D. One piece beginning to fill, others collapsed. 

 November 25 : Eighteen days after section : 



A. Marginal tentacles 2-2.5 mm - showing faint traces of pig- 

 mented bands in two pieces, in other two unpigmented ; labial 

 tentacles 0.5 mm. At aboral end new outgrowth 2 mm. 



B. Marginal tentacles 12 mm., some differences in length ap- 

 pearing in individual pieces, unpigmented ; a few labial tentacles 



1 The complete enclosure of pieces in slime, as in a cyst, often occurs when they 

 remain collapsed for more than four or five days. The slime being secreted all over 

 the ectoderm unites at the infolded ends and forms a complete cyst from which the 

 piece is unable to emerge after a few days. 



D 



FIG. 2. 



' 



