SOURCES OF INTESTINAL WORMS. 
167 
as seems probable^ there were no vegetable matters consumed 
in this instance^ it tends to strengthen one^s conviction that it 
is not the vegetables themselves which ordinarily supply us 
with the nematode larvee^ but rather the putrid water or soil 
which is brought into contact with this kind of food. 
Even should these veg“etables fail^ of theniselves_, to harbour 
parasite larvge destined to complete their life-period within the 
human host_, it by no means follows that they do not act as 
intermediary bearers of entozoa^ known to infest the higher 
animals in their adult state. Were I tempted to pursue this 
subject further^ I might adduce someinterestiug data respecting 
the prevalence of nematodes^ not only in the highest classes 
of plants_, but also within the tissues of certain fungi ; «and 
these parasites_, so far as my observations extend_, are apparently 
destined to take up their ultimate abode within the alimentary 
passages of birds and mammals. The gape disease of game 
and poultry is doubtless propagated in some such way as this ; 
buE as I have fully opened up this subject elsewhere (see the 
Journal of the Proceedings of the Linnean Society) I forbear 
to enter into further details on this head. In course of time I 
hope to witness a wider appreciation of the importance of this 
subject but meanwhile I acquiesce in a distinguished in- 
dividuaPs advice^ and am content to rest and be thankful. 
Water. — I have already incidentally alluded to the un- 
doubted fact of the. existence of larval parasites in impure 
water^ properly so called ; but it remains for me to throw more 
light on this subject ; and also to show that parasitic larv80 
may abound in water which would not ordinarily be regarded 
as otherwise than pure. A glass of apparently clean spring 
water might contain numerous eggs and embryos of entozoa^ 
without their presence being visible to the naked eye ; yep as 
a general rule^ it may be confidently affirmed that in so far 
as entozoa are concerned^ fresh spring water is quite inno- 
cuous. Water_, as commonly supplied from artificial reservoirs 
in this country for household purposes_, is almost absolutely 
harmless ; but the same cannot be said of that which is stored 
up in the large tanks of tropical countries. It is almost abso- 
lutely certain that the larva© of the Dracunculus^ or Gruinea- 
worm (fig. 1 ), are abundant both in artificial tanks and in open 
waters ; but as this parasite is not introduced into the human 
body from water employed as drinh, a consideration of its 
mode of introduction would be out of place on the present 
occasion. I am more immediately concerned to show that the 
people of these islands suffer from entozoa which must be in- 
troduced in our systems along with drink of some kind or other. 
The presence or absence of the eggs and larvge of human 
entozoa in water used as drink is entirely dependent upon the 
locality whence the water is procured; and the particular 
