223 



Plate VII., is a highly magnified representation of two 

 of these heads. 



A good idea of the hydatid, as it exists in the sheep, 

 may be derived from an inspection of Fig 1. PI. VIII., 

 which has been engraved from a sketch kindly fur- 

 nished to me by my friend Dr Kirk of Deal. Fig. 1 re- 

 presents the brain of a sheep two years old, which has 

 been affected with sturdy. The right lobe, a, of the 

 cerebellum orlesser brain, is much distended with fluid, 

 which is enclosed in a membraneous bag, as shown at 

 b, where an incision has been made to expose it, and 

 at c, where it is shining through one of the coverings 

 of the brain, the pia mater. 



The hydatid is found of all sizes, from that of a pea 

 to that of Fig. 2, Plate VII. Large ones are far from 

 rare, and the ventricle is frequently enormously di* 

 tended. The hydatid in the brain from which Fig. 2, 

 Plate VIII. was taken, though not filled to repletion, 

 contained ten drachms of serum. The ventricle was 

 consequently much dilated, as shown at a in that figure, 

 and the usual course and size of the convolutions com- 

 pletely altered. Instead of being folded, like the in- 

 testines, upon themselves, they proceeded, as seen at 

 b b, from back to front of the brain ; while the furrows 

 between them, which are, in the healthy animal, usually 

 too shallow to be measured, were in several places as 

 deep as the length of the lines at c d. 



This excessive accumulation of fluid within the brain 

 leads, as might be expected, to the dilatation of the skull, 

 and to the absorption of its walls, when the bones, 

 young though the animal be when affected with sturdy, 

 can no longer be made to yield. For this reason the 



