282 REPORT OF THE HARVARD AFRICAN EXPEDITION 
tral nervous system in which he is unable to find trypanosomes. In some of 
these cases the pupils may not react to light and while some of the cardinal 
signs of tabes are present, others are lacking. No fully developed cases of tabes 
have been seen by him. 
Chesterman! also says that he has not observed cases of nervous disease 
in association with yaws at Yakusu. 
At Leopoldville, Dr. Van den Branden treats as syphilis such cases of dis- 
ease of the central nervous system as show a positive Wassermann reaction 
and no trypanosomes. He does not consider the diagnosis entirely satisfactory, 
but it is the best method which is practicable there. 
Several other French and Belgian physicians have suggested that there 
exists among the African natives a variety of syphilis which does not produce 
general paralysis and other late nervous symptoms, and Stannus has also 
noted that tabes is extraordinarily rare among African natives. However, 
even in the United States the negro is less likely to develop tabes or paresis 
than the white man. 
With reference to the differentiation of the lesions of the bone in syphilis 
and yaws, the changes which have already been referred to as noted by Maul 
and others might well be regarded as merely clinical variations of the same 
disease. Polak * has emphasized the difficulty in making a diagnosis between 
the tertiary bone lesions of yaws and of syphilis except on the history of the 
case taken in conjunction with x-ray examination. He believes, however, that 
in framboesial lesions, rarefaction of the bone is seen and that in syphilis there 
is thickening and sclerosis. He, however, admits that in congenital syphilis 
a rather similar rarefaction may occur which is difficult to distinguish in ter- 
tiary yaws in a child infected as an infant. Osteitis deformans has been thought 
to be a late manifestation of syphilis. 
Zimmerman * in the study of syphilis as seen in whites and negroes at the 
Johns Hopkins Dispensary in Baltimore, points out that bone syphilis is the 
most frequent lesion of tertiary syphilis in the negro and that neurosyphilis 
is more frequent in white patients than in negroes. The negro, as noted, is also 
less likely to develop tabes or paresis. 
Such authorities as Manson-Bahr,’ Spittel and Araujo, for example, state 
that the mucous membranes are not affected in yaws. However, Noel® has 
observed infection of the mucosa in the Cameroons and believes these lesions 
of yaws have been sometimes overlooked. Apart from the genital and anal 
regions, the secondary lesions of yaws were found in twenty-two cases on the 
mucosa of the mouth, in nineteen in the nose, and in four in the conjunctiva. 
The greatest number of cases were observed in childhood or early life. Castel- 
lani says that lesions of the mucous membrane are not very common and adds 
that granulomatous nodules may develop at the base of the tongue and on the 
1 Chesterman: Brit. Jour. Ven. Dis. (1928), IV, 64. 
2 Polak: Arch. f. Schiffs. u. Tropen-Hyg. (1927), XX XI, 530. 
§ Zimmerman: Trop. Dis. Bull. (1926), XXIII, 85. 
4 Manson-Bahr: Loc. cit., p. 53. 
5 Noel: Ann. de Derm. et de Syph. (1921), II, 72. 
