Experiments on Polarity in Tiibiilaria. 575 



Experi7ne72t 7. With a fine needle it is possible to puncture 

 the membrane over the closed aboral end of the piece and thus 

 to allow a partial escape of the fluid. Two series of experiments 

 of this sort showed that the oral polyp formed as soon as in the 

 check pieces. 



Experiment 8. By tying a succession of ligatures of silk thread 

 around the aboral end it was hoped that more material might be 

 thrown into the circulation; and if its presence had any influence 

 on the rate of polyp-formation, the hydranths should appear 

 sooner than in the check pieces. It was found, however, that no 

 appreciable addition of material could be made in this way, since 

 so little of the ridges breaks down at the aboral end. There 

 was no hastening of the development after tying two or three 

 times. The details may be omitted. 



Experiment 9. A more successful method of introducing ma- 

 terial into the current consists in rolling a glass rod from behind 

 forward for a short distance over the aboral end. In this way, 

 as Godlewski has shown, the coenosarc may be rolled into the 

 interior of the more anterior part, and we have found that some 

 at least of the plug may at times enter the circulation. Two 

 series of experiments showed that the oral hydranth cannot be 

 hastened in this way. 



Experiment 10. By crushing the aboral end it is possible in 

 some cases to introdtice a large amount of substance, including 

 the red pigment, into the circulation. Comparing the rate of 

 development of pieces containing a great deal of material in the 

 circulation, with other pieces containing very little, no diff"erence 

 in time of polyp-formation was detected. 



Experiment II. This experiment was undertaken in the hope 

 of determining what changes take place in the piece during the 

 formation of the oral hydranth. Long pieces were cut out, and 

 then at diff'erent intervals (8, 12, 18, 24 hours, etc.,) they were 

 cut up into short pieces (5-6 mm.), which were placed in a row 

 and the time when their polyps appeared recorded. If there is 

 a movement forward of material in the wall, or if material in the 

 wall is slowly used up from the oral to the aboral end, we hoped 

 that this might be demonstrated by the time of development 



