36 BULLETIN 1053, IT. S. DEPARTMENT OF AGRICULTURE. 



The chlamydospores of Trametes serialis proved no more resist- 

 ant. It is possible, however, that the conditions under which they 

 were formed (in a moist medium) and their previous wetting in 

 obtaining them may render them more sensitive to drying. 



ALTERNATE WETTING AND DRYING. 



The oidia of Lenzites sepwria and L. trabea do not survive alter- 

 nate wetting and drying. Oidia were removed in quantities from 

 an agar plate culture to glass slides. Two slides were retained as 

 checks and the oidia on tAvo others were wet with sterile distilled water 

 and immediately put away until cfcy. One slide was allowed to dry 

 under room conditions, while the other was dried in the presence of 

 calcium chlorid. Germination tests were then made. After 16 hours 

 the controls showed practically perfect germination, while of the wet 

 and dried oidia three Van Tieghem cells showed less than 1 per cent 

 and one 5 per cent germination. Repetitions of the test gave similar 

 results. 



EXPERIMENTS UPON THE DISSEMINATION OF THE OIDIA OF 

 LENZITES SEPIARIA. 



Flask cultures of Lenzites sepmrm and L. trabea obtain a much 

 better start than cultures of the other fungi, because of the oidia. 

 The water in the tube containing the bean-pod cultures used as 

 inoculum becomes a suspension of oidia, and these are distributed 

 all over the flask to start centers of growth, whereas cultures of 

 fungi possessing no oidia can only be spread from the inoculum 

 and consume about one month in covering all the blocks in the 

 flask. In the light of these facts a few experiments were carried 

 out with a view to ascertaining by what means and how easily 

 the oidia. of this fungus might aid in dissemination. It is realized 

 that any points made here are contingent for their importance 

 upon the question as to whether or not the oidia occur naturally. 

 Inasmuch as'Falck (13, p. 319) doubted whether wind would be 

 of any importance in disseminating oidia, the writer set out to de- 

 termine how easily the oidia might be removed from plate cul- 

 tures. A new transfer was inverted over a sterile agar plate, sealed 

 with gummed paper, and set away in the incubator. In the first 

 test with L. sepiaria^ an abundance of oidia were found upon the 

 sterile agar plate after a week. Eepetitions gave inconsistent re- 

 sults, but it was shown that small numbers of oidia may be released 

 during their formation. Shaking a plate culture over a sterile agar 

 plate yielded results similar to those reported by Falck (IS, p. 144). 

 Oidia were dislodged in some cases, but not iii all. The same test 

 was tried with CoUyhia velutipes, and pure cultures were obtained 

 from oidia shaken off. 



