any internal organization resembling that of nematodes enables one 
to differentiate these structures. Numerous structures belonging to 
the fibro-vascular bundles of plants may simulate nematodes, but the 
presence of a spiral marking throughout or of regularly pitted mark¬ 
ings along a cylindrical structure is suggestive of plant material. In 
case of doubt, always examine the object for the internal structure 
which should be present if it is a nematode. 
Various substances simulate tapeworm segments. One which was 
reported years ago by Stiles and subsequently by various writers, and 
which the writer has seen on several occasions, consists of banana 
fibres (Fig. 66), which may have an arrangement very similar to a 
small tapeworm. Blanchard has noted a case in which a piece of 
peach skin was determined as a fragment of hydatid cyst. 
Fig. 73. Ripe spores of corn smut, Ustilago maydis. x 600. From Campbell, 1902. 
Of the things which may resemble flukes the pulp vesicles of the 
lemon and orange deserve mention. Pulp vesicles of the lemon are 
commonly present in lemonade and may pass intact in the feces of 
persons who have recently drunk lemonade. The superficial re¬ 
semblance of these vesicles to flukes has been mentioned by a number 
of writers, including Leuckart, Stiles and Ransom, in connection 
with cases of mistakes in identification of parasites. The lack of any 
internal structure in any way resembling that of a fluke should be 
sufficient to prevent one from mistaking pulp vesicles for flukes. 
Careful washing to remove fecal matter, mucus, etc., is a great aid in 
determining the true nature of supposed parasites. As a matter of 
fact, such mistakes in identification are usually made as a result of 
total unfamiliarity with parasites or as a result of snap judgment. 
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