25 



CONCLUDING REMARKS. 



Before closing - , we wish carefully to examine a few points 

 concerning the life history of Syngamus trachealis, and the propa- 

 gation of the gapes. First, do fowls contract the disease by pick- 

 ing up the eggs, or mature Syn garni containing them? Dr. 

 Megnin's parrot was claimed to have taken the disease from eat- 

 ing, on August 7th, four mature Syngami filled with eggs. The 

 first symptoms of the gapes manifested themselves on August 

 28th, twenty-one days after the feeding, and the bird died Sep- 

 tember 10th, on the thirteenth day of the disease. We believe if 

 the eggs were retained and hatched before they reached the 

 proventriculus, the gapes would result. But we think such a case 

 is exceptional, and not the way in which the disease generally 

 occurs. In proof of this we will not only bring forward the chick 

 fed mature Syiigami (see feeding exp. 11), but also, the general 

 fact that chicks, about fourteen days after they take in the 

 embryos of Syngamus, have large quantities of mature eggs pass 

 through their intestines into the soil. According to first theory, 

 these eggs should hatch within the chick; it would thus become 

 self-infecting, and would almost necessarily die. On the con- 

 trary, after chicks are a few weeks old they generally recover, 

 their windpipes being large so that the usual number does not 

 very materially interfere with their respiration. That the eggs are 

 not contained in the earthworm and thus taken we believe is true, 

 for, in the examination of very many infested earthworms during 

 the past fourteen years, we have never found an egg of Syngamus. 

 It is also evident that the time required to produce the gapes by 

 feeding earthworms is too short for the eggs to hatch and the 

 embryos to pass through their different stages. Again, the eggs 

 are so small they could not be seen, as they were scattered over 

 the ground, and picked up by chicks, and it is highly improbable 

 that they would retain their vitality through the long winter 

 months in this climate, and propagate the disease in chicks the 

 following summer. We are aware that the eggs of various in- 

 sects survive the winter, and continue their species from year to 

 year, but we have found by experiment that the eggs of Syngamus 

 trachealis will not hatch after being kept a few weeks, fatty de- 

 generation takes place, and their vitality is destroyed. We con- 

 sider it unnecessary to bring forward further proof on this point. 

 Dr. Megnin himself abandons the theory, and says: "The birds 

 are infected by drinking water containing the embryos." We are 



