PARASITIC FUNGI IN FISHES. 87 



land shark as the seat of its devastations ; another, 

 as has been long known, one of the Filaria, attacks 

 the eye of the horse ; and not fewer than six species 

 have been detected in the human eye and its ap- 

 pendages. Many of these parasites, as the species 

 of Strongyli, are ascertained to appear first in the 

 blood-vessels of their victims, obscure as the mode 

 of introduction to such a habitat may be ; in the 

 Porpoise they appear next to attack the bronchia?, 

 the lungs then become loaded with tubercles, in 

 which the minute animals are enveloped, and death, 

 by pulmonary consumption, soon results ; the well- 

 known Sturdy or Gid in sheep is produced by the 

 Ccenurus cerebralis, and the Rot, in the same animal, 

 by the Distoma hepaticum. (See Prof. Eschricht's 

 Mem. Edin. Phil. Jour., vol. xxxi. 314.) 



But we hasten to Vegetable parasites, which, it 

 seems now ascertained, exert their deadly agency 

 on every class of the animal series from man down- 

 wards, and more especially, perhaps, on Fishes. 

 They are usually designated Parasitic fungi, and 

 all consist of Cryptogamous plants. In their sim- 

 plest form, as seen in Mould and Mildew, they are 

 minute jointed filaments, composed entirely of cel- 

 lular tissue, the cellules being laid end to end, or 

 collected in a mass under the outer covering of 

 leaves and other parts. In some, the joints sepa- 

 rate, and each appears capable of reproduction ; in 

 others, the cellules which contain the rudiments of 

 the new plants are collected at one extremity, whilst 

 the others serve as the stalk. The fungi spring up 



