PARASITES OF ANIMALS. 1838 
is the Filaria cystica Rudolphi, originally found in a Brazilian 
fish ( Symbranchus laticaudus). It is, therefore, probable that 
the eggs or young embryos of LE. gigas are swallowed by 
fishes, and in their bodies develop into the larval form and be- 
come encysted, and if then swallowed by some mammal, 
migrate into its kidneys to become sexually mature. The 
frequency of these parasites in those animals that feed chiefly 
on fish, such as the otter, mink, and seal, renders this view 
very probable. , 
The Gape-worm of Chickens, ete., (Syngamus trachealis 
Siebold). Figure 82. 
This parasite lives in the windpipe and bronchial tubes of 
chickens, turkeys, pheasants, partridges, crows, wood-peckers, 
and many other birds. In young chickens and turkeys it 
Figure 82. often proves very destructive, by filling up 
~\ the air passages, and thus quickly killing 
\, whole flocks. In some parts of this 
country at least three-quarters of all the 
young chickens and turkeys are some- 
times destroyed by this parasite. The 
worms are reddish in color and have a 
smooth skin, but spiral depressions run 
around the body, giving it a twisted 
appearance. The reproductive organs 
show through the skin, as slender, 
whitish, convoluted tubes. The males 
and females are almost invariably found united firmly to- 
gether, as shown in the figures, the integument of the male 
soon becoming organically united to that of the female, so 
that the copulation is permanent or for life. The females are 
very much larger than the males, becoming about three- 
quarters of an inch in length, and one-sixteenth of an inch 
in diameter. The anterior end, in both sexes, suddenly ex- 
pands into a trumpet-shaped, concave disk, in the middle of 
which thé mouth is situated, surrounded by six small chitinous 
lobes ; the posterior portion of the body of the female is more 
Figure 82.—Syngamus trachealis Siebold ; a, male and female united, natural 
size ; b, anterior part of female, enlarged; c, male, enlarged. From Cobbold. 
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