PHEASANTS IN COVERT AND AVIARY 



its existence in England as an epizootic amongst Pheasants, 

 partridges, and poultry, so that, in all probability, the trouble 

 originally came from the United States. It has been noticed 

 in Germany, France, and Italy, but apparently not until after 

 the discovery of the disease in England. The importation 

 of turkeys from America, of which these birds are natives, 

 may have had something to do with its appearance in 

 England. 



The genus to which the parasite belongs is technically 

 known as Syngamus, and the worm itself as Syngamus 

 trachealis. Worms belonging to the genus have a large 

 mouth and a thick head, the males being smaller 

 than the females, the former measuring about ^th inch, 

 and the latter fth inch. These small worms are 

 round, of a reddish colour, the ovary being double in 

 the female. The eggs of the parasites measure -ji^th 

 inch, and the ova may contain fully formed embryos, 

 which are liberated from the body of the female after the 

 latter has been coughed up by the bird. It is stated that 

 it takes from one to nearly six weeks for the eggs to hatch, 

 provided that the conditions are favourable. Ehlers has 

 shown that an intermediate host is not necessary in order 

 for the embryos to develop into the adult worms. Birds 

 which have been compelled to ingest the ova containing 

 embryos have been found after seventeen days to contain 

 female parasites filled with eggs. The channel or path- 

 way through which the parasites gain entrance into the 

 windpipe has never been satisfactorily demonstrated, but 

 it is very probable that when swallowed they attach them- 

 selves to the back part of the throat and subsequently 

 wander into the air tube, gradually descending towards the 

 main branches of the bronchial tubes. 



Symptoms. — These are very characteristic, but to anyone 



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