330 FUNCTIONS AND INSTINCTS. 



way into the brain of these poor animals and 

 occasions the vertigo ; and the vervecine l and 

 ovine hydatids, 2 which penetrate into their lungs 

 and liver and occasion the rot. It is usually 

 discovered when a sheep is infested by the 

 former of these pests by its turning often and 

 briskly its head on one side ; when it runs very 

 quick, and suddenly stops without any apparent 

 cause ; in a word, when it appears almost de- 

 ranged. Though the progress of the disease they 

 produce is slow, it is generally fatal. Five hun- 

 dred have been counted in the head of a single 

 sheep. The ravages, however, produced by this 

 hydatid are nothing to those occasioned by the 

 other two, which attack the lungs and liver and 

 cause the rot, by which, in some years, thousands 

 perish. 



Some worms are remarkable for their very 

 singular forms or station. One that attaches 

 itself to the gills of the bream, looks like a dou- 

 ble animal, 3 and a kind of fluke, 4 in great num- 

 bers infests the ball of the eyes of the perch. 5 



Though at first view the animals of which I 

 have in the present chapter given some account 

 seem to be altogether punitive, and intended as 

 scourges of sinful man both in his own person and 



1 H. vervecina. 2 H. ovilla. 



3 Diplozoon paradoxum. PLATE I. B. FIG. 4. 



4 Diplostomum volvens. Ibid, FIG. 5. 



5 Ibid, FIG, 6. 



