FACTORS IN THE REGENERATION OF A COMPOUND 

 HYDROID, EUDENDRIUM RAMOSUM^ 



A. J. GOLDFARB 



With Two Figures 



1 Preliminary Statement 317 



2 Effects produced by removing lateral branches or pedicels 319 



3 Effects due to regional differences — age 320 



4 Causes and conditions underlying heteromorphosis 322 



5 Coenosarc, its movements and internal circulation 330 



6 Stolon formation 334 



7 Rate of regeneration 335 



8 Effects of gravity 337 



9 Effects of contact 341 



10 Effects of lack of oxygen 343 



1 1 Effects of direct sunlight 345 



1 2 Effects of temperature 346 



13 Effects of repeated removal of polyps from the same lateral branches 346 



14 Effects of injuries to different parts of the stem 347 



15 Effects of diluted and concentrated sea-water 348 



16 Resume. 



353 



PRELIMINARY STATEMENT 



Loeb's pioneer experiments on regeneration in hydroids, have 

 stimulated a large number of investigators to study the effects 

 of external and internal factors in these animals, especially upon 

 unbranched or slightly branched forms like Tubularia. Most 

 hydroids are affected by the same agencies, but not to the same 

 degree; that while gravity is the determining condition in one 

 hydroid, contact or regional differences or "polarity, " determines 



' I am deeply indebted to Prof. Thomas H. Morgan, who suggested these studies and who ren- 

 dered much valuable advice and assistance to me throughout the course of these investigations. My 

 thanks are due Prof. Edmund B. Wilson for the privilege of occupying the Columbia University Table 

 at the Marine Laboratory at Wood's Hole, Mass., and to Prof. C. W. Hargitt for many valuable 

 suggestions. 



The Journal of Experimental Zoology, vol. iv, no. 3. 



