NEMATODE PARASITES OF BIRDS 37 



and attaining their full growth, both the male and female attaching 

 to the mucous membrane. Sexual maturity is reached 10 to 14 days 

 after the worms reach the trachea. Females attain a length of 15 

 nun. and begin depositing eggs as early as 2 weeks after infective 

 larvae are swallowed. Ransom has reported both mature worms 

 in the trachea and young worms in the lungs 2 weeks after feeding 

 infective material. Ortlepp finds eggs in the feces IT to 20 days 

 after infection. 



A matter of great importance from an economic standpoint is 

 the fact that in chickens, as a rule, only young chicks can be in- 

 fested or do become infested with gapeworms. Post-mortem ex- 

 amination of hundreds of mature chickens have been almost always 

 negative, and attempts to infest such birds are likewise failures, or 

 at least to the extent that the worms seldom become mature and 

 usually die soon if they mature; commonly they either fail to de- 

 velop or undergo only partial development. (Ransom has reported 

 1 well-developed pair and 1 immature pair in a chicken at least 2 

 years old). The worms can only undergo complete development 

 and remain for any length of time in chickens during the first few 

 weeks of life, as a general rule. Ransom has noted that when ma- 

 ture chickens were successfully infected with gapeworms, the worms 

 were often buried in a mass of mucus, the males were dead in many 

 cases, and some of the females were apparently nonfertile and un- 

 natural in appearance. 



On the other hand, gapeworms occur in turkeys, and turkeys be- 

 come infested at any time of life, so far as experiments and ob- 

 servations show. As a result, adult turkeys, which are but little 

 affected by the presence of gapeworms, serve as carriers of infec- 

 tion and young chickens on premises so infected become victims 

 of gapeworm disease. It has been noted in many cases that this, 

 association of turkeys and chickens has been a prominent feature 

 of gapeworm disease of chickens. Apparent!} 7 , the turkey is the 

 normal host of the gapeworm, the disease having been observed in 

 this bird, a native American animal, and in chickens at Baltimore in 

 1799. In 1800, 1807, and 1809, it was observed in chickens in Eng- 

 land, the turkeys and ducks associated with these chickens not show- 

 ing the disease. The turkey, being the normal host, evidently has 

 a normal immunity to the bad effects of the worm, although nor- 

 mally susceptible to infection at any age. On the other hand, 

 chickens, not the normal host, are immune to infection as adults, but 

 are susceptible to infection as chicks and at the same time devoid 

 of immunity to the bad effects. 



Railliet has regarded the magpie {Pica pica) as a carrier of im- 

 portance in France, and it may be that a number of wild birds will 



