Diseases of the Respiratory Organs. 101 



tlie sheep, once introduced into tlie system, will maintain 

 their place in the lungs for the whole lifetime of the host, 

 though no more young worms should be taken in. That 

 of the ox, etc., on the other hand, is more likely to be ex- 

 pelled, and, therefore, often infests its host but for a hm- 

 ited period. 



The Syngamus of the bird has probably the same history 

 out of the body, but this has not been so carefully studied, 



Within the chest the Strongyli live in the small terminal 

 air passages in their young or embryo state, in the larger 

 air tubes when mature, and in cysts in the lung substance 

 when laying their eggs or when about to die that the eggs 

 may be set free and hatched. In the air passages they 

 give rise to bronchitis, in the lungs to pneumonia and 

 deposits resembling tubercles but distinguishable under 

 the microscope by the presence of the elliptical eggs and 

 the embryo worms. 



The Syngamus of birds inhabits the air passages and 

 gives rise to bronchitis. 



In all cases the parasites are most fatal to the young. 

 Although old animals continue to harbor them they prove 

 much less destructive and are often unsuspected. 



SYMPTOMS IN CALVES AND FOALS. VERMINOUS BEONCHITIS. 

 HOOSE. HUSK. 



These are essentially those of bronchitis, with the dif- 

 ference that the Avhole herd is affected and mucus 

 coughed up, containing worms either singly or rolled up 

 in bundles. There is at first only a slight rather husky 

 cough repeated at irregular intervals.. There follows diy 

 staring coat, embarrassed breathing and advancing ema- 

 ciation. Soon the cough becomes frequent, paroxysmal 

 and suffocating, with expectoration of mucus and worms. 

 Or the cough is soft, loose and wheezing, and the patient 

 is weak, hide-bound, with sunken eyes and pale, thin or 

 puffy membranes, dropsical swellings beneath the jaws, 

 chest or belly, and no appetite ; the sufferer may be found 



