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 skull, towards the termination of the disease, generally becomes thin and soft in front of the root of the horn, and in this way offers a spot which, from its being easily pierced, is frequently made the seat of surgical operations. Other parts of the skull also undergo considerable thinning, more so indeed than in front of the horn. The attention of the farmer has hardly, if ever, been called to this fact, though I believe that, for one instance in which perforation occurs in the frontal bone, it will be noticed a score of times on the sides of the head. In a head with which I was favoured by Mr Grieve, Branxholm braes, each temple, exactly beneath the superior extremity of the upright branch of the lower jaw, displayed a circular opening entirely through the bone, wide enough to permit the passage of an ounce bullet. Whatever may produce pressure on the brain, the symptoms which indicate it are nearly always the same. The sheep has a dull, stupid look, turns very often round and round, and will, when water is in its way, stand staring at it till at last, giddy and confused, it plumps fairly in. If, when the symptoms are very unpromising, convulsive movements should occur, they may be taken as a favourable sign, as they indicate a diminution of the pressure on the brain. A minute description of the morbid appearances in hydrocephalus could serve no good purpose, I therefore pass on to the prevention of sturdy. (170.) _Treatment and Prevention of Sturdy._ The variety caused by hydatids can only be prevented by the use of dry, well grown, wholesome food. Dr Jenner found that he could cause hydatids to form in rabbits at will, by feeding them on green succulent provision; and it is well known that this form of sturdy prevails among sheep chiefly in marshy places, as the fens of Lincolnshire. Water in the head is generally induced, as first pointed out by the Ettrick Shepherd, in the _Farmer's Magazine_ for 1812, by the back of the animal being chilled, as is evident from the following facts:-- "1. It is always most general after a windy and sleety winter. "2. It is always most destructive on farms that are ill-sheltered, and on which the sheep are most exposed to those blasts and showers. "3. It preys only on sheep rising their first year, the wool of which separates above, leaving the back quite exposed to the wet and cold. "4. If a piece of cloth or hide is sewed to the wool, so as to cover the back, such a sheep will not be affected with the disease."