IO C. M. CHILD. 



growth and we may suppose that formative stimuli which were 

 insufficient to produce visible results so long as the piece 

 formed an integral part of the parent-body, either become more 

 powerful after artificial section or else that the new embryonic 

 tissue becomes more susceptible. 



A comparative account of the factors of position, size and tem- 

 perature in C. solitarius and the other species studied is rendered 

 unnecessary by the close agreement between all four species. 

 Similar results were obtained in all cases. The only points worth 

 noting here are slight differences in the degree of regenerative 

 power. Ceriantlius nicinbranaccus regenerates less rapidly than 

 the other species. In the small whitish undetermined species the 

 aboral region in which typical regeneration does not occur is 

 relatively much longer than in C. solitaries at the same tempera- 

 tures. During October only about the aboral fifth or sixth of 

 the body is incapable of regeneration or regenerates incompletely 

 in C. solitarius, while in the other species a cut surface only a 

 short distance aboral to the middle of the body is either incapable 

 of regeneration or regenerates incompletely. This species is much 

 less common than C. solitaries and was only rarely obtained ; no 

 opportunity offered of determining its regenerative power during 

 the colder months. Presumably, however, regeneration would 

 have failed to occur except in the region near the oral end. 



One important result of this study may be summed up in the 

 statement that the rapidity and the amount of regeneration in 

 pieces from the body of Ccriantlms depend primarily on the pre- 

 vious relations of pieces to the parent-body, i. t\, on the position 

 and consequent functional condition. This fact is of importance 

 as indicating that the phenomena of regeneration are due not to 

 any special regulatory mechanism which bring about return to a 

 " normal" or "typical " form, but to the same properties which 

 cause growth and differentiation under normal conditions. 



SUMMARY. 



i. The power of regeneration from cut surfaces in Ccriantlms 

 is greatest at the oral end and decreases aborally, becoming null 

 a certain distance from the aboral end. This decrease of regen- 



