Pomona College Journal of Economic Botany. 329 



strains (IV) and (R) developed them in equal intensity, but in strain (E) 

 the pink was scarcely noticeable. This difference in the formation of color 

 gave the (E) strain a distinctly different appearance from the other two. 



The potato strains grew more slowly than the carnation strains. Strain 

 (VII) produced a dense cottony growth about 4 mm. high and began 

 forming a rose pink color in twenty-five days, but this color did not become 

 very intense even in cultures sixty days old. The growth of strain (H) was 

 mostly depressed, the ropy cottony character appeared only in the secondary 

 growth. The first growth was accompanied by the development of an intense 

 lilac color, which later faded to a pale salmon. A pellicle formed over the 

 surface stratum and folded itself about the rice kernels in such a way as 

 to give the culture a very wrinkled appearance. The mycelium filaments 

 of both potato and carnation strains penetrated the substratum and devel- 

 oped their characteristic colors. 



Steamed potato plugs (M8). The carnation strains developed a vigor- 

 ous cottony growth covering the entire plug of each culture in seven days. 

 The usual wine red color appeared the fourth or fifth day, being densest 

 in the pellicle covering the plug and shading to lighter tones in the aerial 

 growth. A sulphur yellow color began developing in twelve to fifteen days 

 and various shades of green appeared in cultures about fifty days old. The 

 colors developed in darkness as readily as in light. The mycelial filaments 

 often extended 20-25 mm. above the tip of the plug, but were without color. 



The potato strains grew more slowly, and the cottony gro\\i;h did not 

 attain such a height as in the carnation cultures. Both strains formed a 

 dense even growth 4-6 mm. high. A rose pink color appeared in eight to 

 ten days in cultures kept in a north window; this color increased in density 

 until it became a rich salmon. Small green sclerotia were observed in a 

 culture of strain (VII) fifty days old. No appreciable color developed in 

 darkness. Both the potato and carnation strains were capable of penetrating 

 through the plugs. 



Steamed heet plugs (M9). The gro\\i;h of the different strains on 

 this medium was very similar to the growth of the respective strains on 

 steamed potato plugs. The carnation strains developed color a little more 

 rapidlj' and with a little greater intensity. The potato .strains did not grow 

 so well; strain (VII) was less dense and only 2-3 mm. high, and strain 

 (H) was always depressed or in ropy masses. 



Raw potato plugs (MIO). Only cue carnation strain and one potato 

 strain were grown upon this medium. The growth of each was very similar 

 to the growth of the respective strains on steamed plugs. The same colors 

 developed in both light and darknes.s. Strain (II) grew less rapidly than 

 on steamed plugs, but developed color equally well. It .should be noted 

 that the method used in preparing the.se plugs probably killed many of the 

 surface cells of the potato, thus facilitating the growth of the fungi. 



