Lesions 



743 



cultivated it upon artificial media, acid vegetable infusions seeming 

 best adapted to its growth. It develops scantily at the room tem- 

 perature, better at 37°C. — ^in from four to five days. In twenty to 

 thirty days a colony attains the size of a httle pea. 



Bouillon. — In bouillon and other liquid media the organisms form 

 little clumps resembling those of actinomyces. They cling to the 

 glass, remain near the surface of the medium, and develop a rose- 

 or bright-red color. Those which sink to the bottom form spheric 

 balls devoid of the color. 



Gelatin. — ^The growth in gelatin 

 is not very abundant, and forms 

 dense, slightly reddish, rounded 

 clumps. Sometimes there is no 

 color. There is no liquefaction. 



Agar-agar. — Upon the surface of 

 agar-agar beautiful rounded, glazed 

 colonies are formed. They are at 

 first colorless, but later become rose- 

 colored or bright red. The ma- 

 jority of the clusters remain isolated, 

 some of them attaining the size of 

 a small pea. They are usually um- 

 bihcated like a variola pustule, and 

 present a curious appearance when 

 the central part is pale and the pe- 

 riphery red. As the colony ages the 

 red color is lost and it becomes dull 

 white or downy from the formation 

 of aerial hyphae. The colonies are 

 very adherent to the surface of the 

 medium, and are of almost carti- 

 laginous consistence. 



Milk. — The organism grows in 

 milk without causing coagulation. 



Potato. — ^Upon potato the growth of the organism is meager and 

 slow, with very little chromogenesis. The color-production is more 

 marked if the potato be acid in reaction. Some of the colonies 

 upon agar-agar and potato have a powdery surface, either from the 

 formation of spores or of aerial hyphae. 



Lesions, — Microscopic study of the diseased tissues in myce- 

 toma is not without interest. The healthy tissue is sharply separated 

 from the diseased areas, which appear like large degenerated 

 tubercles, except that they are extremely vascular. The mycelial 

 or filamentous mass occupies the center of an area of degeneration, 

 where it can be beautifully demonstrated by the use of appropriate 

 stains, Gram's and Weigert's methods being excellent for the 

 purpose. The tissue surrounding the nodes is infiltrated with small 



Fig. 306.— Actinomyces mad- 

 uras in a section of diseased tis- 

 sue (Vincent). 



