12 



to know whether they would serve as a host for the parasite, and 

 thus be instrumental in spreading the disease from farm to farm. 

 The trachea of robins differs, in its size and anatomical structure, 

 from that of poultry, especially at its lower part, where the last 

 ring dilates and forms a second larynx. Syngami generally col- 

 lect from the lower part of the trachea to its middle, and the 

 gapes is simply the effort of the bird to obtain more air through 

 this passage, which is obstructed by these worms. It is evident, 

 therefore, that birds which have a larger trachea would harbor 

 a greater number of Syngami without suffering from the gapes. 

 We see this is the case in chicks after they are several weeks 

 old, for Syngami can often be seen in their windpipes by open- 

 ing their mouths and straightening out their necks. Several 

 worms can thus be seen in large chicks, with very little embar- 

 rassment to respiration. It is also not improbable that, although 

 the embryos may penetrate the esophagus, pass to the lungs and 

 thence to the trachea, the greater part may be coughed up and 

 swallowed before they are able to obtain a hold on its mucous 

 membrane. We know from an examination of chicks that very 

 many of them are thrown off in this way. 



Exp. 13. On July 4th, at 5 p. m., fed a chick, about four 

 weeks old, a large number of Syngami, just hatched, by turning 

 the water containing them down its throat. On July nth, at 7 

 p. m., this chick commenced to have the cough or sneeze char- 

 acteristic of the gapes. July 12th, coughed much more. On 

 July 13th, at 9 a. m., eight days and sixteen hours after the feed- 

 ing, I killed this chick and found one single and twenty-nine 

 pairs of Syngami, 



Exp. 14. On August 14th, at 7 p. m., fed a young robin, just 

 from the nest, a large number of embryo Syngami, hatched in 

 water, as in the preceding experiment. It was kept in a cage 

 hanging under a tree, and fed by the old bird. August 22d. 

 morning: Robin had some symptoms of the gapes, such as rapid 

 breathing, an occasional gape and shake of the head, and was 

 inclined to sit on its perch, instead of standing up, as usual. 

 August 23d: Breathed more rapidly, and evidently quite ill. Au- 

 gust 26th: Robin continued to grow weaker and breathed more 

 rapidly, and at times gaped, but the gaping was not as promi- 

 nent a symptom as in the case of chicks. The robin died the 

 morning of the 29th, the fifteenth day from the feeding. ( to 

 examination three fair sized Syngami were found in the trachea. 



