1904-5.] Ankylostomiasis , or the Miners Worm Disease. 823 
have oxygen. If, for example, they are retained in the deeper 
portions of the faeces they die. We can understand how it is that 
the ova of ankylostoma do not develop in the intestine : (1) the 
temperature is too high ; (2) there is not sufficient oxygen. 
It is not known how long the fully-developed parasite can live 
in the intestine ; some say only a few months, others as long as four 
or five years. As time goes on the patient tends to cure himself ; 
for as the worm cannot propagate itself in the alimentary canal, if 
no re infection occurs the disease gradually wears itself out. It is 
external to the human body, therefore, that the ova become hatched 
into larvae, and it is the larvae gaining entrance into the body that 
cause ankylostomiasis. When at the Erin mine in Westphalia I 
was told by Dr Perner that the larvae could live eight to ten months 
at least in the water and sludge by the sides of the main ways. 
They thrive upon organic matter present in the liquid. Other 
filiform bodies known as rhabdites are also present in the liquid, 
and both of these organisms attack the wooden props, rendering 
them unsafe. So active and wandering are the ankylostoma larvae 
in their habits that, at the present time, in some of the agar cultures 
which Mr Belger and I have been making, the larvae leave the solid 
matter and pass out into the liquid, even moving into the clear 
drops of water that have condensed on the under surface of the lid 
of the Petri dish. It has been stated that outside the body the 
larvae can develop into the sexually matured worm. I have no 
experience of this, and am therefore inclined to doubt the 
occurrence of it. After escaping from the ovum, the larvae 
moult two or three times. 
Mode of entrance of the larvae into the human body . — It was 
formerly believed that the larvae gained an entrance into the 
alimentary canal by men drinking contaminated water or by eating 
with unwashed hands. Dr Looss, of Cairo, whose lantern slides 
I have his permission to show you, sometime ago accidentally 
infected himself by a drop of an ankylostomal culture falling upon 
his finger. A few hours afterwards the skin was red and irritable, 
and a few weeks afterwards he found the ova of the worm in his 
faeces. He therefore experimented upon dogs, and he found that 
larvae applied to the skin penetrated into the deeper subcutaneous 
tissues, and piercing the wall of a small vein, were carried by the 
