138. 
conditions xposure to very intense li¢ht is inimical to myce- 
lial development, and the fungus grows feebly downward into the 
substratum. , however, the intensity of light be decreased 
2: r 
which microconidial formation has occurred abundantly have 
been maintained either in the diffuse light of the laboratory, or in 
the darkness of an incubator. Varying intensity of light there- 
fore does not affect the size of the conidia nor the type of sporo- 
geny, but only the amount and rapidity of conidial formation. 
The same holds true of light of different wave lengths. Exposure 
to the less refrangible rays of the spectrum inhibits the formation 
of conidia, whilst these are produced in abundance in blue or 
violet light. The quality of sporogeny, however, is not affected, 
but only the quantity; either Polyactis conidia are pro- 
duced or there is sterility*. Light cannot therefore be the de- 
termining factor in the production of microconidia. 
sterile form with proliferating conidiophores “forme inter- 
ty of vegetable media the fungus produces spores very 
abundantly between the temperatures of 16° C. and 25° C. With 
raised or lowered temperature mycelial growth and spore A gor 
and the former possessing a slightly greater range. With vary- 
* See Costantin, J. : Bull. Soc. bot. de Fr. 1889; Klein, L.: Bot. Zeit. 
1885; Reidemeister, W.: Ann. Mycol. vii. 1909; Moreau, M. and F.: Bull. 
Soc. bot. de Fr. 1913. 7 
+ Beauverie, J.: Na hr Rend. 128, 1899, and 133, 1901, also Anns. Univ. 
ty dona Nouv. sér. iii. uverie, J., and Guilliermond; Centr. f. Bakt. ii. 
‘ 
