714 



DISEASES OF THE SKIN". 



Pathology. — The disease depends upon a cryptogamic fungus, 

 named the achorion Schonleinii, after Schonlein, who was the 

 first to suggest that the yellow crusts were constituted by a 

 vegetable parasite. The primary seat of the parasite is in the 



Fig. 134. 



Fig. 135. 



Fig. 134. — Branches of achorion Schonlemii in an early stage of devel- 

 opment, growing from' molecular matter, and mingled with epidermic 

 scales, from a very minute favus crust. 



Fig. 135. — Fragments of the branches more highly developed, with 

 numerous sporules and molecular matter, from the centre of an advanced 

 favus crvist. — (Bennett.) 300 diam. 



depth of the hair follicle outside the layer of the epithehum, 

 which covers the root of the hair, and which forms the " inner 

 root sheath of Kblliker." — (Aitken.) 



By making their sections of the favus crusts, and treating 



Fig. 136. — Thalli, mycelia, and sporidia of the achorion Schonleinii, 

 (showing the mode of reproduction. —(Bennett.) 800 diam. 



