23 



stage of ITeocosmospoia. Scbaelit states that it is only one stage of 

 Fusisjwrium solani, lie having found both spore forms attached to the 

 same mj^celiiim. 



K. Klein (Beitrag z. Kent. d. lothen Malzschimels, Mitt. d. osterr. 

 Vers. Stat. f. Braiierei n. Miilzerei, VVien, V, 1892) has also found a Fusa- 

 rium causing bright color reactions on starchy media, but 1 have not 

 seen his paper. 



My conclusions relative to the formation of color by the melon fungus 

 are as follows: 



(a) On neutral or acid media in the i^resence of free oxygen and of 

 starchy foods — e. g., potato, bread, rice, tapioca, wheat, hominy, cucum- 

 ber agar, etc. — this fungus develops in the substratuni a series of the 

 most brilliant colors (I'l. 1, 13), which are then absorbed by the hyph*. 

 These hues include many shades of pink, red, purple, and violet, and 

 in some of the substrata— e. g., bread or boiled rice — are particularly 

 brilliant, changing gradually from shades of purple and rose color into 

 the deepest crimson (rose carthamine). This color is much brighter 

 and purer than any 1 have been able to obtain with Went's Monascus 

 purpurcus. During the development of this pigment the substratum 

 becomes intensely acid (mostly OO2, but some lactic acid according 

 to Mr. K. P. McElroy). If, however, alkaline substances (caustic lime, 

 carbonate of soda, etc.) be added to the substratum in advance, so 

 as to neutralize the acid or acids as fast as formed, no color is devel- 

 oped, the fungus remaining snow white, as in the vessels of the melon 

 plant. If less alkali be added, the colors appear gradually after a 

 time, which is longer or shorter according to the amount added. 



{b) The yellow and brown colors are formed in the presence of an 

 alkali, but apparently not unless sugar is also present. According to 

 the writer's view, the brown stain of the lignified walls of the vessels is 

 due beyond question to the presence of this fungus. Since the lignified 

 walls are much more apt to be stained than the pure cellulose walls, it 

 woidd seem as though the presence in the lignified wall of coniferin or 

 of some related substance may have something to do with the produc- 

 tion of the brown stain. The vascular bundles in melon, cotton, and 

 cowpea contain a distinctly alkaline fluid and the fungus is able to 

 dissolve its way through cellulose walls. If it should also be able to 

 split up coniferin, or some similar glucoside, held in the walls of the 

 vessels, with the liberation of a sugar, then a brown stain might per- 

 haps be formed just as readily inside of the plant as in the alkaline 

 peptone water to which cane sugar was added. 



"^ (3) The color of the peritliecia.—Eo white- walled or colorless perithe- 

 cia have ever been observed on any of the host plants. All have been 

 bright red. They have also been red on a variety of artificial media, 

 particularly those on which they have grown best— e. g., steamed potato, 

 crushed wheat, malic acid agar. Red must therefore be assumed to be 

 their natural color. 



