Journal of Applied Microscopy 



and 



Laboratory Methods 



Volume VI. 



SEPTEMBER, 1903. 



Number 9. 



New Apparatus for Phytopathological Work. 



While working in the plant pathological laboratory of the University of 

 Nebraska during the winter of 1902, we found it necessary to devise a number 

 of pieces of apparatus to meet our peculiar needs. Of these, two have proved 

 so generally useful as to warrant some published description. 

 We wish to acknowledge our obligations to Dr. C. E. Bessey, 

 under whose direction we were working, and also to two of our 

 co-workers, Messrs. P. J. O'Gara and J. L. Sheldon, for assist- 

 ance and criticism. 



A Transferring Oese. — For isolating bacteria, the ordinary 

 poured plate method is sufficient. For isolating fungi, and 

 especially for obtaining cultures of fungi free from bacteria as 

 well as other fungi, this method alone is ineffective, on account 

 of the relatively slow growth of most fungi as compared with 

 bacteria. Bacteria from a single colony may be transferred by 

 merely touching the colony with a sterile oese and thus a pure 

 and isolated culture be obtained ; but the fungus plant or 

 colony that has developed from a single spore must be trans- 

 ferred bodily, unless it produces spores with exceptional 

 promptness. A single bacterial colony will often spread over 

 the surface of a plate before the fungi in the plate have begun 

 to produce spores. Thus it becomes desirable to either transfer 

 the pure colonies (usually single plants) of the desired fungus 

 to new culture dishes; or to remove the contaminating colonies 

 of bacteria or other fungi bodily, leaving the desired colonies 

 /// situ. Moreover, in culture experiments involving growth 

 for a month or more, it is often desirable to transfer a large 

 colony to new or more moist medium ; a simpler process than 

 introducing new medium or water with precautions to insure 

 sterility. At the beginning of our work we made such trans- 

 fers with a two millimeter platinum loop ; but this is not well 

 adapted to the work ; a small colony would slip through, a large 

 one slip off, and the edge was not sharp enough to cut old and dried medium. 

 Moreover, manipulation necessitated raising the cover of the culture dish so 



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Fig. 1. 



