552 EEPORT OF THE COMMISSIONER OF AGRICULTURE. 



Tlifsc birds live almost entirely on earth-worms during a part of the year, and I 

 wi.slied to know whether they would servo as a host for the parasite, and thus he in- 

 strumental in spreading the disease. The trachea of robins differs from that of poul- 

 try in its size and anatomical structure, especially at its lower part, where the last 

 ring dilates and forms a second larynx. Syngami gcuerally collect from the lower 

 part of the trachea to its middle, and the gapes is simply the ellort of the bird to ob- 

 tain more air through this passage, which is obstructed by these worms. It is evi- 

 <U'ut, therefore, that birds which have a larger trachea would harbor a greater num- 

 ber of si/ngami without suffering from the gapes. We see this is the case in chicks 

 after they are several weeks old, for sijngami can often be seen in their windpipes by 

 opening their mouths and straightening out their necks. Several worms can thus be 

 seen in large chicks with very little embarrassment to respiration. It is also not im- 

 probable that although the embryos may penetrate the oesophagus, iiass to the lungs, 

 and thence to the trachea, the greater part maybe coughed up and swallowed before 

 they are .able to obtain a hold on its mucous membrane. We know from an examina- 

 tion of chicks that very many of them are thrown off in this way. 



Experiment 14. — On July 4, at 5 ]). m., fed a chick about four weeks old a large num- 

 ber of syngami jnst hatched, by turning the water containing them down its throat. 

 On July 11, at 7 p. m., this cliick commenced to have tlie cougli or sueeze character- 

 istic of the gapes. July 12 coughs much more. On July l.i, at 9 a. ni., eight days 

 and sixteen hours after the feeding, I killed the chick and found one single and 

 twenty-nine pairs of sijngami. 



Experiment 15. — On August 14, at 7 p. m., fed a young robin just from the nest a 

 large number of embryo syngami, hatched in w.ater, a.s in the preceding experiment. 

 It was kept in a cage, hanging under a tree, and fed by the old bird. August "2"i 

 (morning), robin has some symptoms of the gapes, such as rapid breathing, an oc- 

 casional gape and shako of the head, and is inclined to sit on its perch instead of 

 standing up as usual. August 2'^, breathes more rapidly and is evidently quite 

 sick. August 2G, continues to grow weaker and breathes more rapidly, and at times 

 gapes, but the gaping is not as prominent a symptom .as in the case of chicks. On 

 the morning of the 'JOth the robin died, the fifteenth day from the feeding. On ex- 

 amination three fair-si;scd syngann were found in the trachea, but not enough to fill 

 it up, so as to produce much gaping. 



Eartli-woriiis from infected localities were scut to us by Dr. Walker, 

 in order that wc might confirra his results: 



May 2o. — Thrco chicks wore fed with 8 worms each. One was killed Juno 4. No 

 evidence of syiigames in the entire trachea. Near the pharynx a few blood extrava- 

 sations on the tcsophageal mucous membrane attracted our attention. When care- 

 fully examined several small nematode worms were found in the submucous tissue, 

 tilled with ova. They were not coiled up but lying in a wavy lino. Whether these 

 par.isites were introduced with the earth-worms is a matter of conjecture. June 23, 

 the two remaining chicks were set free. 



July 1. — Two chicks were fed for two days until one had eaten sixteen, the other 

 eiglit worms. July 7, two were fed until each had consumed twelve worms. July 

 24, symptoms pointing to gapes were observed in two of these four chicks. One was 

 killeil July 28, and three pairs of adult syngamcs found in the trachea. The other 

 gaped occasionally, but grew very fast. It was killed August G, and one pair of large 

 syngamcs found attached to tho trachea. 



This pair -vvas torn to pieces on the folio wing day, and the mass, in 

 which wore large numbers of eggs, kept in distilled, water. On August 

 17 tho embryos could be observed moving about in the shell. Two 

 days later many had left the shell. Thus a period of thirteen days, 

 with an average temperature of 80'^ F., was suificieut for their develop- 

 ment. When placed in distilled, water August G, the stage of segmen- 

 tation was not yet passed. Megnin mentions twenty-eight to thirty 

 days as the time required for development at a temperature of GS° to 77° 

 F. The temperature of our laboratory ranged from 76° F. during the 

 day to 880 F. at night. 



On August 19, three chicks, one three days old, and two over a week 

 old, were fed with these embryos and ripe ova. They were suspended 

 in water and injected down the oesophagus with the aid of a i)ipetto, 

 each bird receiving about fifty individuals. 



The younger chicks died on the 1st, 3rd, and Gth of Septeinbef, 

 resijectively. In the last only one pair of syngames was found. Of 



