60 



MICROBES, FERMENTS, AND MOULDS. 



in the horny layer of the epidermis, on which it 

 produces a roughness in the form of dusty pellicles. 

 It penetrates the hair-follicles, but not deeply, and 

 only in the vicinity of the point at which they emerge. 

 The spores of which it entirely consists are generally 

 of an elongated form, and give off buds. 



According to Mallassez, this fungus is the prin- 

 cipal cause of alopecia; that is, the shedding of 



Fig. 32. Epidermic cell of skin 

 covered with hair, affected by 

 Pitgriasis simplex, and covered 

 with spores ( x 1000 diain.). 







8 8 J- 



Fig. 33. Isolated spores, taken 

 from pellicles of Pityrianis 

 capitis simplex: a, full spores; 

 6, empty spores ; c, full spores 

 budding ; d, the same empty 

 (x lOuodiam.) 



hair, and the baldness which eventually ensues from 

 it. It acts in tv/o ways : (l) its presence and multi- 

 plication disintegrate the epithelial layers ; (2) the 

 foreign body irritates the epidermis, producing exces- 

 sive activity in the evolution of cells, and consequently 

 the incessant desquamation which is the most apparent 

 symptom of the disease. The shedding of hair is chiefly 

 due to obstruction in that portion of the hair-follicle 

 which underlies the orifice of the sebaceous glands, and 



