389 
It is well to consider some of these other yaws eruptions, which 
are so well recognised by the natives and described by writers. 
Tubbo is a papilloma, pathologically the same as the frambesia, 
though unlike it in appearance, which breaks through the thickened 
skin of the sole, and is modified by the pressure of the hard epidermis, 
in the same way as the small papules of early psoriasis are modified 
when they appear under the skin of the palm. 
Corn yaws in English-speaking colonies covers all discrete 
papular, vesicular, and even pustulo-vesicular eruptions. 
Crab yaws is simply palmar and plantar psoriasis. It is sometimes 
severe, and becomes a moist dermatitis. More usually it is seen some 
time after the yaws, and is identical with the tertiary plantar 
psoriasis. It is chronic, and very resistant to treatment. 
Pian gratelle, as described by Numa Rat, Alford Nicholls and 
others, is obviously the small papula of syphilis-lichen. It appears at 
an early stage in a profuse crop usually, and, as in European syphilis, 
it may reappear as a late secondary, and its presence indicates a severe 
infection. This tendency to recurrence and this significance of the 
papular eruption is insisted on by writers on both syphilis and yaws 
(cf. Jamieson, Diseases of the Skin, p. 544, and Alford Nicholls, Report, 
p. 285). 
Dartre (or as Nicholls calls it, the macula or squama) may be 
perhaps in some instances the macular rash, which is the earliest skin 
symptom of syphilis. The colour of it cannot be seen on a black 
skin, but when severe and on unwashed skin it may possibly result in 
an exfoliation of the corneous layer of the epidermis; but as 
described it is the syphilitic scaly psoriasis. This is the earliest 
er uption in yaws, and is very common. It is frequently coincident 
w 'th the papular eruption — lichen—when that is present, and some¬ 
times lasts to the stage of the frambesial eruption. Its appearance is 
absolutely characteristic of scaly psoriasis. 
AH these obviously syphilitic conditions are recognised by the 
natives to be essentially parts of yaws as a disease. A patient is 
said t0 have yaws on the strength of any of these, even by medical 
men ’ w khout the frambesial eruption. 
Alford Nicholls and Numa Rat, who have made long and careful 
°bservations of yaws in its earlier as well as later post-frambesial 
' a b e s, describe these conditions as belonging to yaws. Dartre and 
