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 o^ the higher orders of animals. They 

 may be arranged under two general divisions. 1. The Entozoa, 

 or those which reside in the internal parts of the animal, and 2. 

 Ectozoa, those which are confined to the external surface. The 

 latter are chiefly insects, the former worms. 



Linnasus arranged the Entozoa according to the situation 

 which they occupied : viz. such as are developed in cavities 

 communicating with the external air, as intestinal ivornis ; and 

 such as are imbedded in the very suhstaiice of organs, visceral 

 worms. The classification of Rudolphi, however, is founded on 

 the varieties of form, as Neniatoides, Acanthocephala, Trematoda, 

 Cestoides, Tcenia, 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 iris 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 excreta 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- 



