G. A. Turner 
201 
Dr Brock says that persons bathing in the streams skirting Rusten- 
burg complain of severe itching when emerging from the water. Dr 
John Harley noticed that people in Cape Colony often suffered from 
nodular excrescences of the skin, which later became transformed into 
indolent ulcers. He considered these consequent upon the invasion of 
the parasites into the skin when bathing. Personally I have not come 
across any skin eruptions which in any way suggest the entrance of 
any kind of embryos or larvae, unless perhaps a native skin disease 
known as Dwappo. 
I think the preceding statements make it far more probable that 
infection does not occur by the drinking water, but rather through the 
skin while a person is wading or washing in infected rivers or pools, the 
worm entering in the same manner as the larvae of the Ankylostoma 
duodenale. 
It has been urged against the probability of infection occurring 
through the skin while bathing, that monkeys contract the disease, and 
these animals certainly do not bathe, while they constantly drink water 
from streams or pools when they cannot get dew, and in doing so, 
probably immerse their feet at the edge of the water. It seems to me 
most probable that the disease is contracted either by bathing or 
wading in infected water or mud. 
I may add here that Europeans have noted that certain pools in the 
rivers are more fruitful in producing cases of the disease than others. 
The natives on the East Coast state that some cases are produced by 
bathing in certain pools, but they also state that it is caused by drinking 
M’Jumbula spirit (a filthy spirit made by the distillation of a prepara¬ 
tion of manioca root)! 
Cobbold originally suggested that there must be an intermediate 
host in the life history of the parasite, but to the discussion of this 
subject I am not in a position to add any fresh information. 
Incubation Period. 
Dr Stock in his article on Bilharzia, published in the Lancet of 
September 29th, 1906, quotes the cases under Dr Abercrombie’s charge 
which occurred among newly arrived drafts of young soldiers who 
bathed in supposedly infected pool near Pretoria. Of these, the shortest 
time in which symptoms developed after bathing was one month, the 
longest two months. He accordingly concluded that the incubation 
period lasted about six weeks. 
