356 . A. J. Goldfarh 



2 The influence of the presence or absence of lateral branches 

 and their pedicels. Pieces with the lateral branches cut oflF close 

 to the main stem regenerate many more polyps than similar stems 

 from which only the polyps have been removed, for the reason 

 that the ccenosarc tends to withdraw from the pedicels whereas 

 it does not do so from the lateral ends cut close to the stem. 



3 This suggests another closely related factor, viz: the influence 

 of size (/. e., the amount of ccenosarc) on the number and position 

 of the regenerated polyps. Pieces less than i mm. long may regen- 

 erate stems but never complete polyps. Pieces i to i^ mm. long 

 regenerate but one polyp, more frequently however at the basal 

 end. Sometimes one is produced at each end. On larger pieces 

 two or three polyps may appear on an outgrowth at the basal end. 

 Still larger pieces may bear as many as nine basal polyps at one 

 time, while it is rare for more than one apical poylp to be produced. 



4 The influence of the old tissue on the kind of regeneration. 

 Polyps are replaced only by polyps; stems if injured give rise to 

 polyps. Under certain unfavorable conditions proliferation of cells 

 may take place but no differentiation into polyps occurs, and 

 " stolons, " or modified stems, result. If these are cut and removed 

 or grow into a favorable environment polyps, not "stolons, " are 

 regenerated. 



The rate of regeneration varies with the size and age of the 

 piece. Large stems produce polyps quickest at the distal, slowest 

 at the basal region. Medium size pieces regenerate at all the 

 cut ends at the same time. Polyp formation is greatly retarded 

 on small pieces even if the pieces are taken from the distal region 

 of large stems. The two cut ends at any level of a stem regenerate 

 at the same time. The presence of polyps does not prevent, but 

 may retard, regeneration at the basal end. Unfavorable con- 

 ditions, such as lack of oxygen, low temperature, greatly diluted 

 and even slightly concentrated sea-water, gravity (on lateral ends 

 of reversed stems) all retard development. Nothing availed to 

 affect regeneration in less than two days. 



Zoological Laboratory 



Columbia University, New York 



New York City, March i, 1907 



