Account of a Filaria in a Horse’s Eye. 279 
these animals become, that their study constitutes quite an im- 
‘portant branch of zoology. Large and important works have 
been written upon a single species of these parasites, and Dr. 
Nordmann of Germany has lately published a treatise on those 
that inhabit the eyes of the higher orders of animals, They 
may be arranged under two general divisions. 1. The Hntozoa, 
or those which reside in the internal parts of the animal, and 2. 
E'ctozoa, those which are confined to the external surface. The 
latter are chiefly insects, the former worms, 
Linneus arranged the EHntozoa according to the situation 
which they occupied: viz. such as are developed in cavities 
communicating with the external air, as intestinal worms ; an 
such as are imbedded in the very substance of organs, visceral 
worms. ‘The classification of Rudolphi, however, is founded on 
the varieties of form, as Nematoides, Acanthocephala, Trematoda, 
Cestoides, Tenia, and Cystica or hydatids. Cuvier divides them 
into two classes; one characterized by a digestive cavity, and the 
other by the parenchymatous structure. 
A horse is now being exhibited in this city whose right eye 
contains a vermiform animal, floating in the anterior chamber, 
between the ris and the cornea. It was first observed in Febru- 
ary last, when it was about half an inch in length; since which 
time it has increased so as to measure at present about four inches, 
resembling a portion of white thread or bobbin, with an enlarge- 
ment at one extremity of half an inch or more in extent.. The 
animal is confined exclusively to the anterior chamber of the eye, 
in which it swims with the greatest ease and activity; doubling 
itself.in every direction, and performing the most graceful and 
rapid evolutions. It seems remarkable that it should not pene- 
trate the iris, and visit the posterior chamber. Why it does not, 
it is impossible for me to explain. Its movements do not appear 
to excite any sensation in the horse, although a milky cloudiness 
in the aqueous humor, somewhat dims the vision of the eye in 
which it floats. This discoloration is believed by Mr. Camp, the 
owner of the horse, to be owing to the ercreta of the parasite, 
which, he says, are evacuated about once in three weeks, when 
the eye appears much more clouded than at other times. This, 
however, is observed to subside considerably in the course of a 
few hours. Whether this be a fact, may well admit of a doubt. 
We think it more probable that the cloudiness is owing to the ef- 
