TRICHOPHYTONEAE 



475 



to heal; it decreases with distance from the site of the primary lesion). The 

 allergy seems to be a group reaction to the dermatophytes rather than specific 

 for each species (cf. Talice & MacKinnon 1931). Precipitins, agglutinins, and 

 complement fixing antibodies are also produced (Greenbaum 1924) ; also an 

 antibody which greatly checks the growth of the fungus and which may be 

 important in the healing process. These substances affect the severity and 

 duration of successive reinoculations but not the kind of lesion. 



The fact that these organisms multiply and produce lesions only in the 

 horny layer of the skin while they are able to survive in the internal organs 

 and to travel in the blood stream seems to show that the horny layer (as dead 

 tissue) furnishes the only suitable substrate. The susceptibility of man and 

 other animals to certain species probably is related to chemical changes in the 

 composition of this layer or to structural changes in this layer (puberty effect, 

 cf. work of Vamos 1932 showing changes of hydrogen ion concentration of 

 sweat, etc., also Louste, Rabut, & Rivalier, 1933). Also it may be noted that 

 the skin of the living guinea pig, which is not infected under ordinary con- 

 ditions, when removed from the animal furnishes a good substrate for the 

 cultivation of Microsporum Audouini. The variability of virulence and natu- 

 ral immunity has often been noted. A successive passage through experi- 

 mental animals may either increase or diminish virulence. Species which are 

 largely or entirely confined to a single host, or even the usual host of species 

 which infect a variety of hosts, produce little infllammation and little allergy 

 although they are more contagious and of longer duration. 



The particular clinical and histologic form in which the presence of the 

 fungus is manifest seems to be the result of allergic phenomena. This would 

 account for kerion and sycosis being produced by such a variety of species 

 while favus, tinea tonsurans, and tinea microsporica are largely confined to 

 one species each. The same species can produce different types of lesions on 

 different regions of the skin. Allergy would also explain the frequency of 

 lesions in which no fungus can be isolated but which resemble the fungus 

 lesions very closely. (For further clinical discussion see Scholtz, 1932.) 

 Bloch (1928 b) has also given a very extensive resume of this literature to 

 date. These lesions, which are produced by substances transmitted by the 

 blood stream to some distance from the primary lesion, are called trichophy- 

 tides, microsporides, epidermophytides, and favides, depending on the genus 

 of the fungus causing the primary lesion. Curiously, they seem to be largely 

 confined to the prepubertal males, about 90% of the recorded cases being 

 reported on children and 75% on males. In most cases the primary lesion is 

 not the milder type caused by fungi restricted to man, unless the latter are 

 unusually virulent and produce some inflammation. Usually general symp- 

 toms occur, such as headache, loss of appetite, fever, and swelling of the 

 lymphatics in the vicinity of the primary lesion. The blood shows increased 

 leucocytes, especially polynuclears to about 14,500, and some increase in lym- 

 phocytes. The generalized symptoms are usually of short duration. The skin 

 lesions may be lichenoid (lichen trichophyticus), maculopapulose and poly- 



