318 Marine Microbiology 



ten breaks were made per test, a total of 50 feet of twine was 

 needed for each examination. 



The stationary and moving heads of the Dillon Tester were 

 provided with special 'hata' grips adapted to accept small diam- 

 eter twine. The fixed measured rate of cross head travel of the 

 instrument was 1.25 inches per minute. A 250 pound dynamo- 

 meter gauge, with dial divisions of 5 pounds, recorded actual 

 breaking strength of the cordage. Tensile strength is expressed 

 here as the "pull" in lb at the actual breaking point of the Manila. 



The average mean breaking strength of the control twine 

 was 102 lb. Strength measurements of 85 pounds or less for the 

 fungal infested cordage were selected to indicate significant de- 

 gradation. Statistical analyses of standard deviation of infested 

 and control cordage have supported these data. 

 Field Exposure of Manila Cordage 



Fifty lengths of sterilized twine, each 24 to 30 inches long, 

 were attached to two separate wooden frames submerged from 

 The Marine Laboratory pier in approximately eight to ten feet 

 of water. The frames were anchored off the bottom so that the 

 twine was held vertically and subject to vigorous tidal action. 

 The individual pieces of Manila were sterilized in separate petri 

 dishes and were attached to the wooden support frame immed- 

 iately prior to submergence. 



Collections were scheduled at intervals of four to five days 

 over a period of approximately two to five months. At each col- 

 lection, new sterilized sections of twine were placed on the 

 exposure rack. From six to ten pieces of cordage were removed 

 at each collection, one piece of which was transferred immedi- 

 ately to a sterile petri dish for microscopic examination and the 

 subsequent treatment described below. 



The cordage selected for microscopic study was examined 

 for fungal growth initially and at later periods during incubation 

 of the twine. Pieces of fiber of the sample were cut with alcohol- 

 sterilized microscissors and transferred to the surface of a sea 

 water medium containing 1.0 per cent glucose and 0.1 per 

 cent yeast extract fortified with an antibacterial mixture. The 

 latter, added to the culture medium prior to inoculation at a 

 final concentration of 1.0 per cent, consisted of chlorotetracycline 



