In Situ Cultures of Dermatophytes

Studies were undertaken to correlate structure with life cycle in four common species of fungi causing skin disease in man. Hairs naturally infected by Microsporon audouini, M. felineum, and Trichophyton gypseum and scutula of Achorion schoenleini were placed, without any nutrient medium, in van Tieghem cells at various humidities controlled by osmotic solutions of known vapor pressure. These fungi, which while parasitizing the animal body produce hyphae and thallospores only, were then found to undergo a second period of growth on the detached infected host tissue in moist atmospheres. During this phase they produced all the highly differentiated spore forms previously known only on various media. The aerial hyphae, aleuriospores, fuseaux and spirals produced by such in situ cultures are described in some detail. It is suggested that in nature the saprophytic phase is initiated when the infected tissues fall from the animal body in a moist situation, and that this phase may have significance in the epide...