83 



agar the colony was much darker and more dense and the mycelium was 

 darker. The relative rate of linear growth on these agars, as shown in 

 millimeters of colony diameter at the end of 9 days at room-temperature, 

 was as follows: 



On plain agar 70 mm. 



On 25% corn-meal agar. .68 mm. 

 On 50% corn-meal agar. .62 mm. 

 On 75% corn-meal agar. .57 mm. 

 On 100% corn-meal agar. .54 mm. 



When the fungus was planted on plain agar, and pieces (1 cm. square) 

 of corn-meal agar of the above-mentioned compositions were laid on the 

 surface at the edge of a well-developed colony, both color and conidia- 

 production increased with the increase of nutrients. Variation in conidial 

 length on these agars is shown in Fig. C. On this series of agars conidial 

 length was least on plain agar and increased consistently with the strength 

 of the medium. It is to be noted that the coefficient of variability is 

 very high on the 75% corn-meal agar. In Graphs 9 and 10 of this Fig. 

 C, conidial length is seen to be appreciably lower than on full corn-meal 

 agar (Graphs 1-4, Fig. A), and markedly shorter than conidia grown under 

 standard conditions (see Graphs, Fig. K; also App., page 180). Again, corn- 

 meal agar was made in the usual way but the amount of agar was varied, 

 6, 12, and 25 grams per liter being used. In general, in Petri dishes, 12 

 grams per liter proved most suitable. Comparisons between H. No. 1 

 and H. No. 3 on these three media showed at 11 days each that H. No. 3 

 had grown more rapidly than H. No. 1, the ratio being 6.8: 8.5. There 

 was usually a marked difference between these two strains on 12-gram 

 corn-meal agar, more marked than on the others, H. No. 3 showing more 

 definite zonation and more aerial mycelium. 



In Freudenreich flasks, with the 6-gram agar, H. No. 3 made much 

 aerial mycelium on the watery surface; H. No. 1 made only a black pellicle 

 and no aerial mycelium. On 12-gram agar H. No. 1 made small growth 

 of aerial mycelium and the colony surface was black, while H. No. 3 had 

 much loose, woolly mycelium. At 11 days H. No. 3 on each agar had more 

 aerial mycelium and more clumps than did H. No. 1. The most conspicu- 

 ous difference was on 12-gram agar, while on 25-gram agar H. No. 1 had 

 no clumps and H. No. 3 a few. 



There is a clear, definite tendency in H. No. 3 to make more aerial 

 mvcelium and more clumps than H. No. 1, but this is so dependent on con- 



