ACHORION SCHOENLEINII. 169 



it will become clear that the fungi of Herpes tonsurans and 

 Favus are very different, and have, therefore, been treated 

 separately here. H. E. Richter is of the same opinion, based, 

 moreover, on the variation in the size of the parts of the fungi. 

 According to Gudden, favus-fungi are never found in the canals of 

 the sudorific glands or of the sebaceous follicles. 



Growth of the Achorion. 



a. Germination. Remak could not succeed in germinating 

 spores, in pus, muscles, cerebral substance, serum, or on 

 solutions of sugar, but he succeeded very well on an apple, and 

 on his arm. (See author's Appendix? for further information 

 about these experiments.) Gudden states, with regard to the 

 possibility of conveying the disease by means of the spores to 

 other individuals, which was proved by Remak and Bennett, that 

 the transference to uninjured bodies fails, whilst it succeeds very 

 well after removing the outer skin, which may be done either by 

 a vesicator or by scratching. It becomes then merely neces- 

 sary to allow the favus to be tied on such places for 36 120 

 hours. Hebra was unable to notice any propagation of fungi of 

 the favus by means of inoculation, but only redness and the 

 formation of vesicles. 



b. Development. According to Lebert, Remak, and Gudden, 

 there is seen, near old crusts, a small, round epidermal elevation 

 in the midst of them, together with a small yellow body (the 

 favus). If the epidermal layer which covers this body is raised, 

 a drop of pus is sometimes seen to exude, underneath which the 

 little favus lives and thrives, possessing a smooth surface and 

 deeply imbedded in the skin. The pus is often wanting, and 

 the fungus forms a small, firm, yellow spot. If the epidermal 

 layer is removed, and the fungus exposed to the air, it grows and 

 clothes the neighbouring hair, without producing pus. It adheres 

 firmly to the skin, its surface is dry, well defined, and slightly 

 covered with epidermis. On removing the favi new ones spring up. 

 Ignorance of these processes gave rise to the erroneous descrip- 

 tions of the favus by some pathologists, as, for instance, Cazenave. 



The favus passes, according to Bazin, during its development, 

 in three periods, through three different stages, which occur 

 sometimes simultaneously on the same head, and which have 

 been described by authors as separate species Favus urceolaris } 

 F. scutiformis, and F. squarrosus. 



