The preceding data T/ould certainly indicate that certain residuals 

 of chlorine and ranges of temperature applied over comparatively- 

 short periods of time have a very definite effect on the activities 

 of marine borers. Under the conditions of the tests it would seem 

 thats 



1. Lower residuals of chlorine, applied continuously, are much more 

 effective for control than much larger amounts applied inter- 

 mittently, although the latter shorf some degree of graduated ef- 

 fectiveness. 



2. I'Jhen exposed for short periods up to 5 hours, mature Banki-'^ gouldi 

 are able to survive the acti on of as much as 3*00 ppm of chloilne 

 with no apparent ill effects, but when exposed for longer periods 

 the organisms are killed. 



3. Small residuals, when applied continuously, tend to prevent the 

 original infestation by the organiS;-s. . 



U. The elevation of water temperature to IIQOF. for as little as 30 

 minutes per week consistently prevented the infestation of test 

 blocks hy Bankia gouldi, and halted the activity of mature or- 

 ganisms. Raising the temperature to lOQOF. for the same length 

 of time, while apparently having some effectiveness when compared 

 wi.th normal temperatures, vras not as satisfactory as temperatures 

 of HOOF, and 120OF. 



5. Liranoria lignorum seems to be somewhat less affected bj'' the 

 elevated Temperatures than is Bankia gouldi . 



M - 6 



