294 PARASITES OF THE DOMESTIC ANIMALS 



Ssmgamus. Strongylinae (p. 280). — Members of this genus have a 

 ■ slender body of reddish color. The mouth is surrounded by a strong 

 chitinous capsule. The female is much larger than the male and is 

 usually found with the male firmly attached at the vulva which is sit- 

 uated near the anterior quarter of the body. This permanent coupling 

 gives to the pair a forked appearance from which the worm has derived 

 its common name of "forked worm" (Fig. 158). The attachment of 

 male and female is less constant with the species Syn. bronchialis. 



The female of Syngamus trachealis is 5-20 mm. (3/16-3/4) of an inch 

 in length; male, 2-6 mm. (1/16-1/4 of an inch). 



The eggs are elliptical, measuring 85 microns in length by 50 microns 

 in breadth. In the uterus of the female they undergo a variable degree 

 of development, containing when freed a segmented mass or 

 a developed embryo. The eggs are not laid but escape from 

 the body by its rupture, which ordinarily occurs from decom- 

 position, though, according to Railliet, eggs contained in 

 the vagina may pass through the vulva and from under the 

 bursa of the male to the outside. 

 Occurrence and Development. — The condition produced 

 Fig. 158. in fowl by syngami is commonly known in England and the 

 —Syngamus United States as gapes. It is widely prevalent, practically 

 male (at- all of Our domestic birds and many wild birds, especially 

 tached at those in captivity, suffering from it. 



malef "^ ^' ^ peculiar feature in the evolution of Syngamus trachealis 

 is the fact already noted that, due to the covering of the 

 vulva by the permanent attachment of the male, the eggs cannot be 

 extruded and are only liberated by the rupture or disintegration of the 

 mother worm. This may occur within the air passages or after the 

 worm has been expelled. If the eggs meet with water or moist earth 

 the embryos develop and are hatched in seven to forty days according 

 to temperature. Birds may become infested by ingesting eggs or em- 

 bryos, often by eating the worms expelled by infested members of the 

 flock. From the digestive tract the larvae migrate to the air passages 

 where they mature. 



Lesions. — The worms are generally found covered with mucus and 

 in greatest number near the division of the trachea into bronchi. The 

 mucosa, to which they are firmly fixed by their buccal capsule, exhibits 

 at each point of attachment a small purulent tumor, or there may have 

 developed an abscess sufficiently large to obstruct the trachea. The 

 number of coupled worms present may be three or four or twenty to 

 thirty, the smaller numbers being quite sufficient to cause death by 

 asphyxiation, though this will be influenced somewhat by age and the 

 diameter of the trachea. 



Symptoms. — Young birds suffer most from syngamosis, those in 



