288 An Introduction to Medical Mycology 



walls are thick and roughened. There are from four to seven compartments. 

 Microconidia and occasionally racquet mycelium and pectinate bodies may 

 be noted. 



(f ) Filtered ultraviolet rays.— The infected hairs, whether on the scalp 

 or extracted, resemble those infected with M. audouini and are a bright, 

 clear green. Within an infected patch, clear areas devoid of hair are often 

 seen. Colonies of M. lanosum after 10 days are also bright and clear. The 

 center of the growth may be lavender-blue, shell-pink or flesh-ocher; the 

 midzone (not alwavs present) is lavender-blue; the edge is olive-drab or 

 mouse-gray. 



(g) Animal inoculation.— Kittens and puppies as well as laboratory 

 animals are readily infected. Because of this the organism is known as an 

 "animal" Microsporum. 



(h) Differential diagnosis.— This is discussed in the section on diag- 

 nosis of M. audouini, pages 284 and 286. 



3. MICROSPORUM FULVUM (MICROSPORUM GYPSEUM; 

 ACHORION GYPSEUM) 



Apparently imported from South America, this fungus is occasionally 

 seen in New York. There are few reports of its occurrence elsewhere in the 

 United States. It is another example of an animal Microsporum and has 

 been called the cause of dog favus. Lesions caused by M. fulvum are usu- 

 ally confined to the scalp and glabrous skin, and the patients are almost 

 always children. 



(a) Clinical characteristics.— In the patients with infections of the 

 scalp which we have studied, a uniformly and severely inflamed patch was 

 noted. The scalp was hypersensitive, and the area of infection was edem- 

 atous and often kerionic. The prognosis for early cure is good. Treatment 

 should be conservative. On the glabrous skin, ringed lesions of dull red 

 with a clearing center and a vesicular border may be noted. As a rule 

 scaling is scanty. 



(b) Immunologic reactions.— Intracutaneous trichophytin tests invari- 

 ably elicit sizable reactions in patients with infections due to this fungus. 

 This is not surprising in view of the character of the lesions. 



(c) Microscopic features.— Hairs infected with this organism may 

 show a sheath of spores arranged in rosaries, probably representing the 

 early stage of invasion, and also spores with no linear arrangement. The 

 resemblance to an infection due to A. schoenleini is sometimes striking. 

 When the invasive stage of the infection is over, the appearance of the 

 fungi in fresh preparations is indistinguishable from that of other Micro- 



