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XXXVII] Nicholls remarks that, in examining them with a lens, "they are seen to be apparently pushed up from the rete Malpighii through the horny epidermis, which breaks over their summits and splits in radiating lines from the centre, the necrosed segments curling away from the increasing papule. When

Fig. 90.—Another case of yaws.

the papules become about a millimetre in height and breadth, a yellow point may be observed on the summits ... consisting not of a drop of pus under the epidermis ... but of a naked, cheesy-looking substance, which cannot be wiped away unless undue force be used. Frequently a hair will be observed issuing from this yellow substance, thereby indicating that the hair-follicles are the centres of the change