58 UNIVERSITY OF WISCONSIN STUDIES 
TABLE V.—OIDIUM 
Time Exposed (hours) 
Date Age of Culture 
Growth No growth 
June 21, 3915 
July 10, 1915 
July 18, 1915 
TABLE VI—PENICILLIUM GLAUCUM 
ime Exposed (hours) 
Date Age of Culture 
Growth No growth 
September 30, 1918................ 2 
October 25, 1913 
October 30, 1913.. i “35 
DMLY AG's TOIR. iG 64 crsiciendie daa aisle TS RO esc toltanen 
An examination of the above tables shows that the mold 
spores possess an extraordinary resistance to direct sunlight. 
This resistanee was so unexpected that in the earlier trials 
the cultures were exposed for only a few hours; this time was 
gradually lengthened until in the last trials the exposure was 
continuous for four or five days during the long days of July, 
and vet Aspergillus niger and nidulans never failed to grow. 
The other species showed some irregularities, but possessed 
remarkable endurance. The irregularities may be due to a 
failure to infect the paper strips, for in no other way can we 
explain the discrepancy in the case of Aspergillus fumigatus 
which withstood 42 hours of exposure one time and only 18 
hours in an earlier trial. 
It is diffieult to explain this extraordinary resistance of 
mold spores as compared with bacterial spores which rarely 
survive more than five hours. The fact that these spores are 
colored suggests that this pigment exerts a protective influence; 
