Celsus’s description is so important, that we shall give a considerable part of it in his own language. He mentions two species of the favus, or κήριον. “Alterum est subalbidum, furunculo simile; sed majus, et cum dolore majore: quod ubi maturescit, habet foramina, per quæ fertur humor glutinosus et purulentus; nec tamen ad justam maturitatem pervenit. Si divisum est, multo plus intus corrupti, quam in furunculo, apparet, altiusque descendit. Raro fit nisi in capillis. Alterum est minus, super corpus eminens, durum, latum, subviride, subpallidum, magis exulceratum; siquidem ad singulorum pilorum radices foramina sunt, per quæ fertur humor glutinosus, subpallidus, crassitudinem mellis, aut visci referens, interdum olei: si inciditur, viridis intra caro apparet. Dolor autem, et inflammatio ingens est, adeo ut acutam quoque febrem movere consuerint.” For the second species he recommends as external applications a dried fig, linseed boiled in mulse, and emollient plasters. To the other he also directs us to make applications containing figs, turpentine, rosin, &c. But when these have not the effect, he recommends us to cut the fungous excrescences down to the sound flesh, and then to dress the sore upon general principles. (v. 28.) The above account of an affection of the scalp, which we have often met with in practice, is the most accurate to be found in any author ancient or modern. We are even in doubt whether the complaint be at all noticed in modern works on surgery. It is not to be confounded with the Porrigo favosa, or Porrigo scutulata, of Dr. Bateman. Avicenna’s description of the achor and favus is far from distinct. (iv, 7, 3, 1.) The favi appear to be the pustulæ capitis quæ dicuntur _alsahafa_ of Alsaharavius. (Pract. i, 11.) His description, however, is by no means distinct. He approves of general evacuants, and local applications of a stimulant nature, such as sulphur, mercury, birthwort, &c. Serapion has not described the favus very accurately, but he has given a full account of the treatment. He properly forbids strong applications at first. (i, 3.) Rhases recommends much the same applications as Serapion. (Ad Mansor. v, 16.) SECT. XXXVI.—ON THE SIMPLE ULCER.