282 Account of a Filaria in a Horse’s Eye. 
ficient proof of the fact. We can discover no true circulation in 
these animals, but in several there appear to be one or two nerv- 
ous cords, which surround the mouth, and extend the whole 
length of the body along the internal surface of the envelope. 
The intestine is for the most part straight and of considerable 
width; the esophagus is contracted, and in some species the 
stomach is distinctly developed. The animal is of both sexes 
and propagates by ova, which are extremely small. 
The Filaria is of a long, slender, filiform shape, and perfora- 
ted at the anterior extremity by a round oval aperture. Some 
species bear considerable resemblance to the Gordius, or hair- 
snake, which abounds in fresh-water brooks and ponds. It prin- 
cipally occurs within cavities which do not communicate exter- 
nally,—in the cellular membrane, the substance of the muscles, 
and different viscera, and occasionally in the eye. The follow- 
ing embrace a few of the more common species. 
1. Filaria medinensis, or Guinea worm, is the most common 
and best known species. It is found chiefly in warm climates, 
where it is often seen in the morning dew, sometimes ten oF 
twelve feet long, and not thicker than a horse-hair. It is this 
species which insinuates itself under the skin, where it may be 
felt like a tense string. Here it burrows and grows to a length 
of several feet, without exciting great pain or uneasiness, until 
the skin is perforated by the animal. It is usually drawn out 
with great caution, by means of a piece of silk tied around its 
head. If it break bya too violent effort, the part remaining 
grows with redoubled vigor, and often occasions a fatal inflam- 
mation. When drawn out, it is found to be elastic, white, trans- 
parent, and contains a gelatinous substance. Though usually 
met with in the lower extremities, it sometimes occurs in the in- 
-teguments of the head, neck and trunk, and Baron states that he 
saw two instances of it under the mucous membrane of the eye 
ball. 2 
2. Filaria bronchialis. This species is described by Treutlet, 
and so named from its occurrence in the lungs of persons labor- 
ing under phthisis. It has also been called Hamudaria lymphat- 
- tea, and by Rudolphi, Haularia sub-compressa. This is also 
met with in the lungs of the inferior animals, especially when 
affected with tubercles. Dr. Hodgkin states that he often found 
the Filaria in the lungs of the boa constrictor, = 
