H. 8. Stannus 
365 
a pigmented spot from an albino, and also to the association of an unusual develop- 
ment of lanugo and of defective teeth with albinism. 
The condition of the teeth suggests enamel deficiency, and is one which I did 
not meet with when examining the teeth of 1500 natives of all ages (not albinos) 
for statistical purposes. 
One of the interesting points which has been brought to light by the investi- 
gations of Pearson and others is that in albinotic hair, while granular pigment is 
absent, diffuse red or yellow pigment is present, and the same is true of some 
kinds of red hair among Europeans. The relation of this diffuse pigment to 
granular pigment has not however been I think generally recognised. From the 
microscopical examination of the various hairs above described I think there can 
be little doubt that the granular pigment is formed from the diffuse pigment by 
some process allied to precipitation (compare hair from new-born infant child 
of Private Jumbe, from Mwana Ngala, from Pamandhe, also from Sawali and 
Moyichandi) *. 
Loss of colour may be accompanied by a reversed process (compare hair from 
Kause, an old female lunatic). 
A similar process may take place iu the skin, as evidenced by the band of 
diffuse colouration beyond the area of granular pigment found in the section 
of prepuce (Lijuni). 
The plan of the localised leucotic patches may be palaeogenetic as suggested 
by piebalds with white belly markings and flare, or there may be a segmental 
distribution (see case of girl H. in whom the area is limited strictly by the 
mid-line). 
One believes therefore that pigmentation is due to an internal secretion, that 
light and other climatic conditions are determining factors, that a ferment may 
play some part, that the pigmentation of the skin is due to melanin produced in 
the cells of the epidermis, and that therefore structure also must be taken into 
account, that in albinism in its various grades and in dynamic forms of leucosis 
one or other or several of these factors have to be taken into account. 
Addendum. One may say that in ordinary natives the colour of the iris is 
always some shade of brown. There is one exception. The iris in a few otherwise 
ordinarily dark natives may be of a greenish colour with no element of brown, 
a very striking feature, and known as "jeri-jeri" by the natives, who say it 
resembles the eye of a cat. 
* [It seems difficult to establish such a conclusion until very elaborate chemical investigations of 
the two types of pigment, lipochrome and melanin have been made. The microscopic investigation of 
hundreds of samples of hair, albinotic and non-albinotic, are given in Chapter VIII of the Monograph , 
but they tell so far as much in favour of the independence as of the dependence of the two types of 
pigment. Ed.] 
Biometrika ix 
47 
