SOUECES OF INTESTINAL WORMS. 
165 
essential importance to adopt the cleanliest habits, and to 
avoid swallowing small snails and other minute animals, which, 
despite aU onr precautions, will occasionally have escaped 
notice. 
Three other human fluke parasites exist, the 
larvae of which are, in all likelihood, obtained 
from sources similar to those above mentioned ; 
but as these parasites have not, at present, been 
found to affect the inhabitants of these islands, 
I forbear to point out the formidable symptoms 
which one of these entozoa is known to occa- 
sion in om* species dwelling in Africa. I must 
confess, however, that I think it not improba- 
ble that, ere long, some of our home-bound 
colonists will be the means of introducing this 
parasite {Bilharzia hcematohia, fig. 4) and its 
terrible helminthiasis into this country ; and if ^.—BUharzia 
.. . *i -m T p 1 1 hcBmatobia; x 10 
it once gets among us, it will, i tear, also be diam. 
exceedingly difficult of extermination. That it would flourish 
here there can be little doubt, seeing that eggs and living 
specimens have already been found in this country, imported 
both by human and monkey hosts.^^ 
Fruit. — A very prevalent notion exists throughout all 
classes of the community, that the eating of fruit, 
especially if it be unripe, gives rise to one of the 
most common parasitic maladies with which we are 
acquainted. I allude of course to the symptoms 
occasioned by the little thread- worm {Oxyuris 
vermicular is, fig. 5). With the view of bringing this 
popular idea to the test of experiment, I tried to 
rear embryonic Oxyurides in apples and pears. At 
first I thought I had succeeded, but a subsequent 
repetition of the original experiment, combined with 
a re-investigation of the entire circumstances of the 
case, have only served to persuade me that we have 
no evidence whatever to show that any of our 
nematode invaders are derivable from fruit. In yiq. 5 .—Oxy~ 
other words, it is not at all hkely that fruit is ever “q* ^vermu 
an intermediate bearer of any of the parasites which diam. 
ordinarily occupy the human body. Certainly a great many 
evils affecting, children are laid to the charge of ripe and 
unripe fruit, but, in so far as entozoa are concerned, these 
surmises are probably groundless. It is, doubtless, within the 
bounds of possibility that one or other of the two species of 
human Ascaris, properly so called, may be introduced along 
with fruit into our stomachs ; but here, again, one naturally 
asks whether the larvae may not have been adherent to the 
surface of the fruit so introduced ? From what follows in the 
