CHAPTER XX 



Dubious Fungous Forms and Artefacts 



T 



HE forms to be described will be observed fairly frequently, and their 

 appearance should be readily learned. 



1. THE MOSAIC FUNGUS 



The majority of those who have examined many scrapings have expressed 

 the opinion that the so-called mosaic fungus (Weidman) is an artefact. 

 Stumpf claimed that the mosaic fungus is made up of free fatty acids. 

 Davidson and Gregory stated that the mosaic fungus consists of choles- 

 terol crystals; Cornbleet and his eo-workers agree with this observation on 

 the basis of their experiments using fluorescence microscopy. Some still 

 hold that it is a degenerate form of a pathogen. Dowding and Orr re- 

 viewed the literature and cited their own experiments as evidence that 

 the mosaic fungus is transformed from T. gypseum. They have observed 

 ( as we have ) that ordinary hyphae and mosaic segments are occasionally 

 to be seen in apposition; that normal spores and hyphae are sometimes part 

 of the mosaic formation, and that the amount of mosaic material increases 

 while the numbers of living fungi decrease during the healing of lesions. 



The appearance of the mosaic form was described by Weidman as 

 follows: 



The segments are irregularly shaped, and are separated from each other by nar- 

 rower or broader, but definite spaces; they have a moth-eaten appearance, and their 

 edges and corners are rounded off. The) do not have any organized internal struc- 

 ture; arthrospores are not visible within the segments. But it is the arrangement ol the 

 mycelium that raises the question whether this is fungus— not so much that it occurs 

 in smaller and larger patches, but that the mycelium ramifies and anastomoses around 

 the individual epidermal cells in such a way as to suggest that air or other relraetile 

 matter had become imprisoned between the cells. These hyphae vary in width, until 

 finally one recognizes only threadlike filaments coursing between the ceils. It requires 

 fine discrimination to come to the conclusion that these are fungus and not inert inter- 



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