TRICHOPHYTONEAE 435 



meant any tiny insect larva, such as a bookworm or clothes moth. A combina- 

 tion of the Greek and Roman ideas has given us our English ringworm as a 

 general term for these fungus infections. 



• The fungi of this group often attack the young of the species, before 

 sexual maturity, in man (Sabouraud 1910 et al.), the horse (Brocq-Rousseu 

 1926) and neat cattle (Jeanselme, Bloch & Hutinel 1923). After puberty, 

 many species disappear completely while others grow much more slowly, 

 probably because of changes in concentration of hydrogen ions; e.g., Vamos 

 (1932) found the pH of the skin before puberty (hairy areas) to be 6.2-6.5 

 while after puberty it had increased to 4.5-5.6. Medication with gonadal ex- 

 tracts has been used with the aim of controlling the disease by hastening the 

 advent of puberty in those cases in which puberty is expected shortly (Neuber 

 1930). Occasionally species (usually of the subgenus Bodinia of Favotri- 

 chophyton) , which are generally confined to the prepubertal stage, are found 

 on senile individuals or very rarely on normal (?) adults. Although the case 

 histories do not mention the matter, it would seem quite probable that gonadal 

 deficiency existed in these adults. Other organisms, such as those of sycosis 

 and to a less extent, species of the genus Epidermophyton, seem to be largely 

 confined to the male after puberty. In the case of eczema marginatum and 

 tinea interdigitalis, no age or sex is wholly free, although the greater portion 

 of the cases are found in young unmarried males, shortly after puberty, 

 particularly among students, athletes, and soldiers. 



The lesions are essentially benign, because they are limited to the super- 

 ficial horny layers of the tegument, and applications of relatively simple anti- 

 septics suffice for their destruction. If the fungus reaches the hair, the latter 

 continues to grow normally. The parasite invades it as fast as it forms, so 

 that if it is not treated, the fungus may continue its growth for many years. 

 Although many species have been described from different parts of the world, 

 there are but few important ones in any one locality, usually not more than 

 two for any one clinical type of lesion. 



Since members of this group are practically confined to the horny layer 

 of the epidermis or to keratinized structures, such as hair and nails, we may 

 discuss the lesions produced in the different structures in this order. While 

 theoretically an organism might invade all of these structures, such cases are 

 very rare, for the greater part of the organisms are tjqjically confined to one 

 of these structures and on passing to another produce only mild, evanescent 

 lesions. 



In the horny layer of the epidermis the lesion varies both with the organ- 

 ism and the position of the epidermis. Practically all members of the group 

 start their growth in this layer, those infecting hair follicles, hair and nails 

 soon penetrating into those structures, scarcely affecting the epidermis save 

 to produce a scaling. Of those which remain in the horny layer of the 

 epidermis, we may consider separately those of the dry portions, those of moist 



