gS CLINICAL BACTERIOLOGY AND HEMATOLOGY 



it may be distinguished by the fact that its spores are arranged 

 in an irregular mosaic, and not in chains. Its mycelium, which 

 consists of long threads, lies in the interior of the hair, whilst 

 the spores form a thick mass outside (Fig. 28, and Plate VI., 

 Fig. 4). This sheath of spores projects a short distance above 

 the surface, and may often be seen with the naked eye. The 

 outside of the hair is destroyed, and the surface of the hair 

 eroded ; the former feature serves to differentiate it from all 

 other varieties of ringworm, and from favus. 



This fungus usually attacks the scalp in children, and in them 

 it dies out spontaneously about the age of sixteen, whilst other 



Fig. 28. — MiCRospoRON Audouini.* 



varieties of ringworm often do not. It is very rare in adults, and 

 it rarely attacks other regions than the head. It is thought by 

 some to be always caught from a human case of the disease, but 

 there are reasons for thinking that it may be derived by infection 

 from the horse or cat. 



The most important clinical fact about the M. Audouini is that 

 ringworm caused by it is extremely intractable, and may run a 

 prolonged course in spite of the most skilful treatment. 



The Trichophyton (or Megalosporon) endothvix attacks the interior 

 of the hairs, and forms long chains ; it always involves the hair just 

 inside the cuticle, being in reality an endo-ectothrix. Its spores 

 are somewhat larger than those of the preceding species, but the 

 difference is not great ; the organism is most easily recognised by 

 the chain-like arrangement of its spores, and by the fact that 



* Fig. 28 is from Curtis's ' ' Essentials of Bacteriology ' ' (Longmans) . 



