Use of Platform Method of Growth in Demonstrating Pigments of Certain Pathogenic Fungi. ∗

Abstract

The platform method of growth has been described. 1 , 2 A piece of blotting paper is bent so that there is a horizontal portion which will just fit into a test tube with 2 legs to act as supporting members. The liquid medium is added almost to the horizontal portion. The tubes are plugged with cotton and sterilized. The plant is made on the horizontal portion. The 2 legs keep the plant supplied with moisture and nutrient by absorption. Care must be taken that the blotting paper contains no substance inhibitory to the organism.

In these experiments the organisms were allowed to grow 6 weeks. The following tubes were planted: pulpit tubes with 1% peptone, 4% dextrose and 1% asparagin, 4% dextrose; broth tubes with 1% peptone, 4% dextrose and 1% asparagin, 4% dextrose. The pH was adjusted to 5.6. Growth took place at room temperature in diffused light.

The organisms studied were: Achorion schoenleinii, Epidermophyton cruris, Epidermophyton rubrum, Indiella americana, Microsporon felineum, Monosporon apiospermum, Trichophyton granulosum, Trichophyton gypseum asteroides, Trichophyton gypseum lacticolor, Trichophyton niveum, Trichophyton purpureum, Trichophyton sulfureum.

Achorion schoenleinii. Asparagin medium. In broth there is a small mycelial, intact growth, continuous with the sunken plant; this growth is white and on its surface is a shredded appearance resembling poor grade cotton; all growth is submerged and there is slight milkiness of the broth. On the platform there is sparse growth.

Peptone medium. On broth there is a wrinkled, pellicle of light tan covered with sparse powder; the pellicle tends to form irregular small cones at the medium centrally; there is a small bit of fuzzy mycelium in the bottom of the tube; the medium is amber colored. On the platform is a low sparse growth, very little extending down the stilts and a brown color where the mycelia stick to the glass of the tube; there is no growth in the broth, but the medium is somewhat lighter than the control.