G. A. Turner 
209 
( b) The light coloured animated ovum, with a spine looking like 
a thin thorn projecting from the surface. 
(c) The ovum with a very thick spine, producing the appearance 
almost of a division of the lower end of the egg. This represents, I 
believe, the calcified state in the terminal spined ovum. 
(d) Shells of the lateral spined ova from which the embryos 
have escaped. 
As regards the first two forms of the lateral spined form, it must be 
noted that at times, on first looking at them, it appeared as though they 
had no spines at all. But immediately on pressure being brought to bear 
on them through the cover-slip, a spine shoots out. I think this is in 
most cases an optical delusion, and that what really happens is that the 
ova were lying with the spines on their inferior surface, and that 
pressure on the cover-slip causes the eggs to turn over, so bringing the 
spine suddenly into view. 
I may mention that I frequently, when examining scrapings from 
the mucous membrane of the bladders and intestines, found empty ova 
shells, from which the miracidiaor embryos had escaped. In Cobbold’s 
Entozoa, it stated that Griesinger found a number of empty eggs in 
the left ventricle of the heart. Other authorities have doubtless 
observed the same fact. I have also, when examining perfectly fresh 
specimens, especially those taken from the mucous membrane of the 
rectum, observed that the slightest pressure has caused the ova to burst 
and the field of the microscope has been suddenly populated by numbers 
of rapidly moving miracidia. These statements suggest to my mind 
that the ova do occasionally dehisce while still within the human 
system, and explain occasional evidences of recrudescence of the disease. 
Pathological Anatomy. 
The changes caused by this parasite are principally to be seen in 
the urinary and alimentary systems. 
(1) Urinary System. 
Calculus. I am dealing with this subject separately, as I consider 
my observations are of especial interest. I notice that in Egypt the 
frequency with which natives suffer from stone in the bladder is 
ascribed to Bilharziosis. In South Africa, of the 66 autopsies I have 
made on natives infected with the disease, in which the bladder has 
been particularly examined, I have not once found a stone. Further, I 
