6 Transactions of the South African Philosophical Society. 
underneath it would gradually increase in thickness. At the same 
time the epidermis is permanently wearing off at its outer side, as 
is well demonstrated by its rough or rather torn and’ lacerated 
surface. The result of both processes would be that the parasite 
would be gradually but completely removed from the skin. And 
this actually takes place with the shells of the dead parasites, their 
place being afterwards indicated by a smooth depression in the 
epidermis. The living Tubicinella, however, cannot.be got rid of in 
this way, for as it dissolves that part of the epidermis with which 
its base is in contact, at the same rate at which new epidermal 
tissue is being formed underneath it, the layer of epidermis which 
separates it from the corium remains of the same thickness, and the 
parasite retains its place, its shell disintegrating at its outer end at 
the rate at which it grows at its base. 
