CARCINOMA OR THR THYROID IN SADMONOID FISHES. 
501 
as A . duodenale with reference to dogs, are sufficient to indicate that stray parasites may enter the body 
through the skin as well as through the mouth, and perform extensive migrations through the tissues 
and even undergo a partial development before they die. The possibilities as to the amount of damage 
such stray parasites may do are interesting. They may, for instance, have more injurious effects on 
the unusual host than on the animal to which they are specifically adapted, much as in the case of 
various parasitic protozoa which do not injure certain animals considered to be their usual hosts, but 
are very injurious to others considered unusual hosts. The two eases are of eourse not strictly com- 
parable as there would be no multiplication, at least no repeated multiplieation, in the case of the 
nematode like that in the case of the protozoan. The introduction of microorganisms by nematode 
larvae is another possible source of damage, and this applies not only in the case of stray parasites but 
in the case of those entering their proper host animals. Many parasitic nematodes have plenty of 
opportunity during the early stages of their free living existence while they are actively feeding upon 
the organic materials in the medium, commonly fecal matter which surroimds them, to pick up injurious 
microorganisms, and these it is quite conceivable may be carried with them on their later migrations 
and finally deposited where damage will result. Looss (1911, Rec. Egypt. Govt. School Med., Cairo, 
V. 4, p. 557), for example, suggests that Ancylostoma larvae which have developed in feces might retain 
some bacteria in their intestine and evacuate these as soon as they arrive in the body of their host, and 
that this if it occurred might have something to do with the skin lesions which accompany Ancylostoma 
infections. 
Returning to the nematodes in the thyroid of the dog, it has not seemed advisable to venture an 
opinion as to the genus or even the family to which the parasites may belong. In order that they may 
not be left nameless I have designated them as Agamonematodum gaylordi, thus placing them in a col- 
lective group, which is used for convenience of reference to include various immature nematodes, 
whose sexually mature stage is undetermined. The following brief description is based on an individual 
the anterior portion of which is present in the sections on a slide labeled “ Dog 17. K. 1-22-12.20, Nem. 
2’’. (Fig. 123.) 
AGAMONEMATODUM GAYLORDI. 
Length uncertain, but apparently less than i millimeter; maximum width 3570 Head apparently 
with 3 lips, each supplied with a small papilla. Diameter of head at level of papillae 207^, increaising to 
2471 at a distance of 2074 from the anterior end, then rather suddenly constricted to 2074, after which the 
diameter of the body gradually increases, reaching 3274 at the level of the nerve ring, which is located 
about 10074 from the anterior end of the body. Mouth very small, communicating directly, without 
intervening larynx or mouth capsule, with the esophagus. Esophagus near its anterior end 
measures about 1674 in diameter, is then constricted slightly, corresponding with the constriction of 
the body, and gradually increases again in diameter, attaining a size of about 1874 in the neighborhood of 
the nerve ring. Length of esophagus uncertain, but exceeds 16074. The anterior end of the body is 
supplied with narrow lateral cuticular wings, which extend posteriorly an unknown distance beyond 
the esophageal region. 
Hos t . — Dog {Canis f ami Ha ris ) . 
Location. — Thyroid gland in small tubercles. 
Locality. — Craig Brook, Me. 
The nematodes were not found in the two dogs examined in 1910, one of which had 
marked thyroid hyperplasia and the other a nearly normal gland, but serial sections were 
not available. In all (3) of the puppies which had marked hyperplasia and were given 
drinking water in which were suspended scrapings (dog 16, dog 17, and dog 22) nema- 
todes are present. In the white mongrel adult dog with the highest degree of diffuse 
parenchymatous hyperplasia and degeneration (dog 18) they are also present. In the 
control for this dog, the mother of the puppies, which received boiled water (dog 19), 
they are not present. In the control puppy no. 21, which received boiled water, they 
