13 



not enough to fill it up, so as to produce much gaping. The 

 rapid breathing, which was the most prominent symptom, was 

 readily accounted for by extensive deposits in both lungs, more 

 especially the right. The lower part of each lung was affected, 

 and the diseased condition doubtless resulted from the irritation 

 of the parasites.* Many other feeding experiments with chicks 

 have been made in different years since the above. 'All of them 

 thoroughly confirm 'the foregoing ones in every respect, and it 

 is deemed unnecessary to detail them here. Experiment 13 

 proves that the embryo of Syngamus does not have to pass 

 through an intermediate host to obtain any change in structure, 

 or increase in development, that the earthworm is simply a 

 bearer, in which it lives in its embryonic condition, and through 

 which it obtains access to its final host, the fowl. This chick 

 was kept in the barn and all other sources of the disease excluded, 

 which was not the case with the robin. The time from the feed- 

 ing to the production of the disease in the chick was the same 

 as when earthworms were fed, which is good evidence that it is 

 the embryo instead of the egg in those which causes the disease. 

 It may further be stated that in the examination of many infested 

 earthworms I never yet found one to contain the eggs of Syn- 

 gamus. In dissecting the robin I found an embryo just emer- 

 ged from the esophagus into the lung. It was a short distance 

 above the proventriculus, was sexually developed, being a male, 

 and thus affords convincing proof that they enter the lung this 

 way. In a chick I also found a pair of Syngami just united, on 

 the posterior part of the esophagus, which had the appearance of 

 having been penetrated by these worms. I have also found the 

 embryo lying beneath the mucous membrane of the esophagus. 



ARTIFICIAL CULTURE. 



Exp. 15. On September 23d, 1883, a mature Syngamus filled 

 with eggs was placed in a small glass dish with a little water, for 

 the purpose of observing the development of the embryo, the 

 structure of the young worms and the time required for them to 

 hatch. We also thought that by comparison in this way they 

 could be more positively identified in the earthworm. The dish 



*This condition resulting from parasites is mentioned by Dr. N. II. Paaren, in the 

 American Entomologist, Vol. 2, page 149; also, by Dr. George M. Sternberg, from M. 

 Larrlaine, in an article on the "Production of Tuberculosis by Inoculation," in the 

 American Journal of Medical Sciences, Vol. LXXXIX, page 18. 



