62 A MANUAL OF THE ASPERGILLI 



culture, or the culture itself may grow out through the plug and contaminate 

 other cultures or experiments. Surface sterilization of the outside of the 

 tubes and poisoning the plugs takes care of molds, as well as mites. 



Spraying: Oily sprays, as selected fractions from petroleum, avail- 

 able from commercial sources, even kerosene, distributed with a "gun" 

 that produces a mist penetrating and filling all cracks, crevices, open spaces 

 among apparatus or furniture and clouding the whole atmosphere of the 

 laboratory, have been found effective in carrying down mold spores and 

 bacteria from the air and ridding the laboratory of mites, insects, and 

 vermin. 



PRESERVATION OF DRIED SPECIMENS 



Mold cultures lose many of their characteristic and diagnostic features 

 upon being dried. Nevertheless, dried herbarium specimens serve a useful 

 purpose in preserving type material which might otherwise be lost. Details 

 of morphology are often difficult to establish from such material, but group 

 characteristics are preserved and over-all colony appearances can be recog- 

 nized after many years. The retention of culture tubes or petri dishes 

 containing such dried specimens constitutes a reasonably satisfactory means 

 of preservation, and the material contained therein approximates as nearly 

 as is possible the cultural picture of the growing colony. Glass tubes and 

 dishes, however, are cumbersome and easily broken, hence may prove 

 unsatisfactory if frequent handling is necessary. For many years we have 

 employed an alternate technique with generally satisfactory results. Rep- 

 resentative portions of colonies grown in petri dishes are cut with a large 

 cork borer, lifted out with a spatula, and dropped into paper pill boxes 

 where they are allowed to dry. These can then be stored in larger boxes 

 or attached to herbarium sheets for filing. The boxes should be provided 

 with tight-fitting lids, and for greatest convenience should measure approxi- 

 mately l\ inch in diameter. Aspergilli stored in this way prove useful in 

 many comparative studies. They cannot, however, under any condition, 

 take the place of carefully handled living cultures. 



