ASEXUAL REPRODUCTION IN SAGARTIA 217 



cycle of incomplete mesenteries alternating therewith the 

 number of orange stripes is absolutely limited and their positions 

 are determined. The only occasion thereafter for the formation 

 of new complete mesenteries and new orange stripes is a division 

 initiating a new regeneration. 



EXTERNAL INDICATIONS OF INTERNAL STRUCTURES 



Much information concerning internal structures may be ob- 

 tained by a consideration of all the external features of indi- 

 vidual anemones. Differences in ground color of the column wall 

 or in the width or intensity of color of the orange stripes per- 

 sisting in spite of changes in the state of expansion of the speci- 

 men, especially if associated with unevenness in length, breadth, 

 or whiteness of the white bars, give indication that fission has 

 occurred and that regeneration is in progress. These features 

 may, especially in the earlier stages of regeneration, present 

 differences sufficiently sharply marked to indicate the precise 

 boundary between old and regenerating tissue. An obstacle of 

 no little importance is the liability of unequal contraction in 

 different parts of the wall of the column to alter for the moment 

 the intensity of all colors and the relative positions of the 

 stripes. The intensity of coloration of the new as compared 

 with the old part, the width of the new sector, and the presence 

 or absence in it of a new white bar or of new orange stripes, give 

 basis for judging within broad limits the stage of regeneration 

 of internal parts. Frequently the presence of three or more 

 sectors of different ages may be readily determined, and the 

 different sectors may show various stages of regeneration. When 

 two regenerating areas of nearly the same age lie adjoining each 

 other, it is often difficult to recognize them as two. In certain 

 cases it is practically impossible to distinguish by external 

 observation the constituent parts of such a double regeneration. 

 WTienever the number of orange stripes of an apparently single 

 regenerating region exceeds eleven, it is almost certain that two 

 regenerations are involved. When the orange stripes are faint 

 or when they are less than seven in number in a given regenerating 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 2S, NO. 2 



