256 BIOLOGICAL ACTIVITIES OF MOLDS 



A number of tests have been devised to detect damage in fabrics 

 or fibers caused by molds. Only one type will be briefly mentioned 

 here. Fleming and Thaysen/* Prindle/^ and others have devised 

 tests involving the swelling of the fibers with carbon disulphide- 

 sodium hydroxide or suprammonium solutions (preceded by stain- 

 ing with Victoria Blue B where the latter swelling solution is used). 

 The fibers are then examined microscopically. AVhen treated with 

 such swelling solutions, normal cotton fibers present an appearance 

 like a string of beads. The layers of cellulose swell except where 

 they are enclosed by the cuticles and thus are constricted. The fibers 

 of mildewed fabrics, on the other hand, do not present this appear- 

 ance because the cuticles have been damaged or destroyed and the 

 cellulose has been altered. 



Although the use of a number of antiseptics, organic compounds, 

 copper or zinc organic salts, and mercuric compounds have been ad- 

 vocated in controlling mold growths, the only sure way by which 

 textile or textile material destruction by microorganisms can be pre- 

 vented is by maintaining the moisture content of the materials 

 below 8 per cent. This method of preventing mold destruction of 

 fabrics or raw fibers is not feasible in all cases where the materials 

 must be outdoors or where the fibers have to be wetted during the 

 processing. 



Thom, Humfield, and Holman '^^ have devised a test to measure 

 the mildew resistance of cotton fabrics. Sterilized samples of test 

 fabric are placed on mineral salts agar in Petri dishes and inoculated 

 with the spores of Chaetomium glohosum. After incubation for 14 

 days at 28° to 30° C. the strips of fabric are washed and raveled 

 down so that they contain the same number of threads as one inch 

 of the original sample contained. The tensile strength is then meas- 

 ured by a suitable apparatus. More recently, Greathouse and his 

 associates ^^ devised another test for evaluating fabric treatment for 

 mildew resistance, a modification of one Greathouse and others ^* 

 had used previously. Their test involves placing strips of the 

 samples to be tested on cotton batting strips placed in bottles laid 

 on their sides. Sufficient liquid nutrient medium is added so that 

 the test sample is in contact with the liquid, 5 to 10 ml. of the free 

 liquid being present. These workers used both C. glohosum and 

 Metarrhizium sp. in the test. The samples are incubated for 7 days 

 at about 30° C. and then washed, dried, and broken on the Scott 

 tester. Greathouse and his coworkers -* discussed the difficulties in- 

 volved in the evaluation of the results obtained from this test pro- 

 cedure. 



