PARASITES OF MYCETOMA 663 



In size the grains vary from a millet seed to a pin's head and consist of 

 innumerable, closely interwoven hyphse. 



1. Microscopical appearance. Under the microscope the grains will be 

 found to be composed of very slender closely interwoven filaments straight 

 or wavy and measuring l/u-l'5/x across. In the thinner parts of the film the 

 filaments appear to be branched and at the 



periphery of the tangled mycelial masses there 

 is a tendency to a radiating arrangement. 

 Small irregular swellings measuring about 2/x 

 are often seen at the extremity or in the length 

 of the filaments, but clubs are never seen. All 

 these details can be made out by staining with 

 methylene blue or dilute carbol-fuchsin and 

 examining under a magnification of 400 or 500 

 diameters. 



In cultures the same arrangement is seen but 

 the filaments are more slender and their breadth 

 does not exceed 1/x. In cultures two weeks 



old the ends of the filaments are often broken 



. i , . , FIG. 312. Discomyces madurce. 



up into regular, ovoid segments which are (After Vincent.) 



larger than the filaments themselves, and con- 

 stitute the fertile hyphae. The spores are refractile, oval in shape, and have 

 sharply defined outlines. They measure T5/X-2/A broad and are variously 

 arranged in pairs, groups of three, chains or in large masses. When sown in 

 a new tube of broth they elongate at one end, giving origin to a short rod 

 with rounded ends. 



Staining reactions. Discomyces madurce stains readily with the basic 

 aniline dyes and retains the violet in Gram's method. Eosin and safranin 

 stain the parasite feebly, iodine colours it yellow, hsematoxylin, violet. The 

 spores stain well with the basic dyes and by Gram's method. 



Sections. Excise some small pieces of skin containing either the young, 

 hard, painful nodules or nodules which are softening. Examination of the 

 material is rendered somewhat difficult on account of the ease with which the 

 grains drop out of the tissues. Vincent recommends the following technique : 

 Harden the pieces of skin successively in 60 per cent., 80 per cent., 90 per cent, 

 and absolute alcohol. Embed in paraffin. Fix the sections on slides and 

 stain with Orth's alcohol carmine and Gram's stain. 



Under the microscope the whole of the diseased area is seen to form a large 

 tubercle in the centre of which is a mycelial mass having the characteristics 

 described above. 



2. Cultural characteristics. Discomyces madurce grows at all temperatures 

 between 20 and 40 C. but best at 37 C. It is a strict aerobe. Growth is 

 always very small in amount on ordinary media : vegetable infusions are the 

 most useful for growing cultures of the organism. 



To isolate the parasite in pure culture sterilize the surface of the skin, 

 incise one of the nodes with a sterile bistoury, introduce a fine pipette through 

 the incision, and aspirate the contents of the tumour. Sow the material on 

 one or other of the following media. 



Culture media. Vegetable infusions. An infusion (15 grams to the litre) 

 of straw or hay (the aromatic plants must be removed) forms an excellent 

 medium, as does an infusion of potato (20 grams to the litre). Cultures are 

 best sown in Erlenmeyer flasks, on account of the free supply of air. 



After incubating for 4 days at 37 C. small greyish flocculi appear, some of 



