342 A. J. GoUfarb 



the lateral branches within the tube were in contact with the glass. 

 The results were very decisive. 



TABLE 18 



No. branches 

 Polyps regenerated on 3 days 6 days removed 



Cut ends, within the tube 0% o 88 



Cut ends, outside of tube 56% 116% 34 



In no case did regeneration occur on cut ends within the glass 

 tubing. After six days these stems were removed from their tubes, 

 and regeneration then proceeded normally at nearly all the cut ends. 



Experiment ig. Other experiments under somewhat different 

 conditions illustrate further the inhibition due to contact. Each 

 stem was rolled in a thick sheet of cotton, which was then immersed 

 in water. No hydranths regenerated. Cotton about half as thick 

 was used and several hydranths appeared in three days, but by 

 the sixth day they were gone and did not reappear thereafter. By 

 using cotton one-half as thin again, a still larger number of polyps 

 were produced, which disappeared less rapidly than in the pre- 

 ceding case. The results were similar when stems were placed 

 between two flat layers of cotton, so arranged that a stream of 

 sea-water continually flowed through the cotton. When removed 

 from the cotton, the stems regenerated readily — provided they had 

 not been kept too long in it. 



Experiment 20. On one side of a dish of sea-water stems were 

 loosely placed, on the other side a larger number of stems were 

 crowded together into a groove 4 mm. wide by 5 mm. deep and 

 somewhat longer than the length of the stems. Table 20 gives 

 the detailed results. 



TABLE 20 



Indicates the total number of polyps observed on the following days 

 3d 4th 5th 6th 7th 8th 9th loth nth No. of stems 



1 Crowded stems 22120021 2 10 



2 Not crowded stems .... 10 23 10 2 3 6 6 9 16 6 



3 Crowded stems 20 15 7 4 4 6 10 12 39)^ 12 



4 Not crowded stems 40 35 20 27 36 22 20 20 19J 7 



*Stems had been scattered. 



The crowded stems regenerated only at the free unentwined 

 branches on the top of the pile, and regeneration was less than in 



