478 A MANUAL OF BACTERIOLOGY 



The endothrix variety commences to grow in six or 

 seven days, and on maltose agar in about a month forms 

 a rounded patch with a central crateriform depression, 

 the whole being dusted with fine white powder (Fig. 53) ; 

 on potato, powdery stars develop tinged with yellow and 

 usually without discoloration of the medium. 



The cultures of the ectothrix form are variable. They 

 commence on the third or fourth day ; some develop 



FIG. 53. Culture of the ringworm organism. Endothrix form. 



whitish smooth, or wrinkled growths ; others, from the 

 dog, form dry, brown, wrinkled, powdery growths ; others, 

 of bird origin, form purplish growths. 



Microscopically, all the fungi show masses of mycelial 

 threads with spores. They stain with the ordinary anilin 

 dyes and also by Gram's method, and can be mounted in 

 glycerin jelly in the manner described at p. 475. 



Macfadyen found that the ringworm organism produces 

 an active peptonising enzyme, and seems to increase the 

 solubility of keratin when grown on it ; no inverting 

 enzyme could be isolated. 



