RESISTANCE OF MOLD SPORES TO SUNLIGHT 59 



doubtless this is true in a measure, but there still remains the 

 fact that Oidium with colorless spores also shows remarkable 

 resistance. 



The fact that mold spores 8 re relatively lighter than other 

 spores would suggest that they have succeeded better in elim- 

 inating water from their protoplasm and hence are better able 

 to resist adverse agents. How far this may really enter into 

 the explanation it is difficult to say. 



The results help to explain the prevalence of mold spores 

 in air where they greatly preponderate over bacterial spores. 

 While bacterial spores can resist the action of sunlight but a 

 few hours, mold spores can resist this action for days. Indeed, 

 it is doubtful whether sunlight is able to kill mold spores. 



SUMMARY 



Spores of the following molds were exposed to direct sun- 

 light on paper slips in glass petri dishes: Mucor Asper- 

 yillus niger, Aspcrgillus fumigatus, Asperyillus nidulans, 

 Oidhun, Penicillium glaucum. The results show that mold 

 spores are able to withstand 58 hours or five days of continual 

 exposure to the intense rays of a summer sun. 



Apparently, sunlight possesses slight, if any, germicidal 

 powers upon mold spores. This fact helps to explain the 

 greater prevalence of mold spores than bacterial spores in 

 air, for the latter are killed usually within five hours. 



