54 BULLETIN 140, "UNITED STATES NATIONAL MUSEUM 



dissimilar, the right being 2 to 2.17 mm. long and the left 700/* to 

 1.1 mm. long. 



Female 10 to 15 mm. long. The tail (fig. G7) is long, narrow, and 

 pointed, the anus 1 mm. or more ( ? ) from the tip. Vulva not salient, 

 situated slightly posterior of the middle of the body. From vulva 

 to bifurcation of the uterus is about 4.5 mm. Eggs thick-shelled, 

 ellipsoidal, 63 to 71/a long by 38 to 48/a wide, according to most 

 authors, or 68 to 75/x long by 36 to 38/x wide, according to Uribe, not 

 yet segmenting when deposited; Uribe notes that the shell is thick- 

 ened at one end of the egg, and that this thickening may enclose a 

 lenticular clear space. 



Life history. — Eggs pass in the feces of the host and develop in 

 7 to 12 daj^s under favorable conditions of temperature (18 to 29° C.) 

 and moisture to the point where each contains an infective embiyo. 

 Eggs develop in water, physiologic saline solution, on salt solution 

 agar, in 1 : 1,000 corrosive sublimate or 1 per cent sulphuric acid. 

 When these eggs are swallowed b}' suitable birds, the embryos are 

 released from the shell and develop to adult worms. Within l 1 /^ 

 hours after ingestion of the eggs, the larvae are found to have 

 emerged into the small intestine. At the end of 21 hours they are 

 present in the ceca, and sometimes in the colon, and are 250/a long by 

 18/i wide. In 10 days they are 790//. long by 45/x wide. The entire 

 development in the bird takes place in the digestive tract, the worms 

 being mature in 21 days. There is no wandering of the larvae to 

 the lungs as is possibly the case in Asca/ridia galli (p. 82), although 

 the Oklahoma Experiment Station reports that all chicks fed with 

 larvae died of pneumonia in 8 to 10 days. Galli- Valerio and also 

 Latulle and Marotel have reported the occurrence of the larvae in 

 tumors in the ceca, and Graybill has found the larvae in the mucosa. 

 Uribe finds the young worms in the cecal glands from the second to 

 the fifth day after infection, subsequent development taking place in 

 the lumen of the intestines, but about the ninth day worms may be 

 found with the anterior third of the body inserted in the cecal gland. 

 He found mature females in 56 days. Earthworms may ingest the 

 eggs and carry them to the intestine, and birds may become infested 

 by eating such earthworms; the earthworms may also pass these eggs 

 in their casts and thus infect otherwise uninfected ground. 



Eggs from worms collected from chickens killed and chilled at 

 34° F., then frozen for 3 days at 0° to 10° F., then kept at 0° to 

 10° F. for 6 months, were found to develop embryos in 75 per cent 

 of the eggs examined by Riley and James. According to Graybill, 

 ova may survive desiccation for 16 to 18 days; eggs in soil contained 

 live embryos after 8 months. 



Distribution. — Cosmopolitan. This species is very common in the 

 United States. 



