ISOLATION AND PURE-CULTURE METHODS 



39 



Sealing cultures. In order to seal the tubes permanently, sealing 

 wax may be used after pushing the plug in somewhat below the 

 level of the glass. Ordinary beeswax is also effective if a little ster- 

 ile paraffin is first poured over the plug and permitted to harden. 

 The length of life of a culture 

 may sometimes be preserved in 

 this way for several years. 



If the cultures are placed in a 

 damp place, as in a closed box or 

 case, with a surface of water 

 evaporating, so as to diminish the 

 loss of water from the tubes them- 

 selves, it would be well to wipe 

 out the case carefully with a dis- 

 infectant before use. Where it is 

 desired wholly to prevent evapora- 

 tion under normal conditions of 

 aeration a different method is nec- 

 essary. The cultures may be put 

 into a clean beaker or tin vessel 

 fitted with a zinc screen, or cross 

 wired with copper, serving to sep- 

 arate the tubes from contact one 

 with another. After thoroughly 

 flaming the corks the vessel of 

 tubes may be placed in a small 

 dish or plate of water containing a 

 little potassium dichromate and 

 the whole covered with a clean 

 bell glass. 



Cultures by sporophore frag- 

 ments. In his studies upon Agar- 

 iais campestris the writer ascer- 

 tained that fragments of the inner tissue of the hymenophore of 

 this fungus placed upon a sterile nutrient medium, such as bean 

 pods, sterile compost, soil, etc., would readily develop a vigorous 

 mycelium. In order to secure cultures of this particular species 

 promptly, it was necessary (i) to use proper sterilization and 



Fig. io. Culture op Polyporus 



sulphurews (Bull.) Fr., a Species 



Tough in Texture. (By Tissue 



Fragment Method) 



