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- 

 cipal) y 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 or 

 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 by a 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. Filaria hronchialis. This species is described by Treutler, 

 and so named from its occurrence in the lungs of persons labor- 

 ing under phthisis. It has also been called Hamularia lymphat- 

 ica, and by Rudolphi, Haularia S2ib-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. 



