FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 37 



Attempts were next made to dislodge oidia from agar-plate cul- 

 tures by air currents from an electric blower delivering 1.4 cubic feet 

 per minute. The apparatus was so set up that at least a part of the 

 oidia removed would lodge on sterile agar plates. From cultures 

 with a very heavy development of oidia, a very few were dislodged, 

 as determined by microscopic examination of the surface of the 

 sterile agar plates and subsequent growth. An electric fan making 

 a much stronger current of air removed larger, though not consider- 

 able, numbers of oidia. Oidia on wood blocks from cultures were not 

 removed any more readily, inasmuch as they are formed only in 

 moist atmospheres and are themselves moist and sticky. The same 

 procedure was tried with other species showing secondary spores in 

 culture. Individual oidia or small clusters were likewise dislodged 

 from agar cultures of Collybia velutipes. The stronger current of 

 air removed a few of the chlamydospores of Fames officinalis, but 

 oidia could not be removed from cultures of Coniophora cerebella 

 or Merulius Jacrymans or chlamydospores from cultures of Trametes 

 robiniophila or Fomes igniarms. It is thus seen that secondary 

 spores of most of the species mentioned do not appear to be adapted 

 to dissemination by wind. 



Oidia are readily removed by contact. Prints can be made upon 

 glass slides or cover slips by simply allowing the glass to touch the 

 surface of a culture. More sticky substances like agar retain more 

 oidia than glass. The obvious application of these facts is insect 

 dissemination, for insects with sticky feet and hairy or bristly ap- 

 pendages should be able to remove and carry away large numbers of 

 the moist oidia. A cockroach caught in the laboratory was placed 

 upon agar cultures of Lenzites sepiaria for a few minut.es. Exami- 

 nation of the roach's appendages under the microscope disclosed 

 large clumps of the oidia stuck to the tarsi. Another roach placed 

 upon an agar culture was transferred to a sterile agar plate, allowed 

 to remain a few seconds, and then the plate was incubated. In three 

 days the plate showed a winding growth of Lenzites sepiaria and 

 contaminations, chiefly Penicillium, presumably where the roach had 

 walked over the agar during his captivity. A cockroach was then 

 placed in a flask containing a wood-block culture of Lenzites sepirivia 

 and examined alter a few minutes. A few oidia were found Upon 

 tli.- pads of the tarsi and on the bristles of the legs and antenna) (PI. 

 VIII, fig. 3). 



Water will dislodge large quantities of oidia from agar or wood 

 cultures. Sterile water dropped from a pipette upon the inoculum 



of a new transfer will cany or splash large numbers of oidia on the 



surrounding sterile agar. 



From tin- above results it is concluded that oidia occurring either 

 on wood or agar are moist. sticky spores, not adapted to air dissenii- 



