Account of a Filaria in a Horse's Eye. 295 



ova are thus introduced into the blood, carried to every part, and 

 there only hatched, where they meet with a suitable 7iidas or 

 pabulum, and other circumstances are favorable to their develop- 

 ment.* Thus are they transmitted from parent to offspring, and 

 thus do we account for the fact that each species of animal has 

 its own parasites. In this manner the ovum of the Filaria was 

 deposited in the eye of the horse now exhibiting in this city, 

 there hatched into existence, and where it may now be seen, 

 reveling in an element which appears, so far as we can judge, to 

 be highly congenial to its nature and habits. 



New York, June 24, 1840. 



Postscript. July 22, 1840. — Since writing the above I have 

 seen numerous Filaria in eels and black-fish, chiefly on each side of 

 the spine ; and the fishmen inform me that they have seen them 

 in the eyes of fishes. Mr. A. Halsey also stated at the meeting 

 of the Lyceum, after the above paper was read, that he had often 

 seen Filaria in coleopterous and other insects. I have ascertained 

 that they are extremely tenacious of life, and will not only bear 

 freezing, but a temperature little inferior to that of boiling water, 

 without depriving them of life. Professor Owen of London, the 

 celebrated comparative anatomist, estimates the number of ova 

 in one Ascaris lumbricoides which he examined, at 64,000,000. 

 [Lancet, June.) The fecundity of the Filaria is probably not 

 inferior. 



* " A very curious disease of the eye has in a few instances been observed. The 

 common symptoms of opiithalmia appear, as injection of the conjunctiva, dimness 

 of the cornea, weeping and swelling of the cornea. These are properly attended 

 to, but the inflammation increases; and on very close examination, a small white 

 worm, about the size of a hair and an inch in length, is found swimming in the 

 aqueous humor, or that fluid which is immediately behind the cornea. Now it is 

 at once evident that the only way to get rid of or to destroy this worm, is to punc- 

 ture the cornea and let it out ; and this method has been resorted to. In some 

 cases, however, not many days pass before another worm makes its appearance, 

 and the operation is to be performed a second time, and the horse eventually loses 

 that eye. A veterinary surgeon, M. Chaigraud, who seems to have had most ex- 

 perience about this, says that three or four days before the appearance of the 

 worms, one or two minute bodies, of a reddish vjhite color, are seen at the bottom of 

 the anterior chamber of the eye. He also says, that the disease appears about June, 

 and is not seen after December. There is no difficulty about these animalcules get- 

 ting into the eye, for there are undisputed instances of their passing through the 

 smallest capillaries, and being found in almost every tissue." — Youatt on Cattle, 

 p. 293. 



