452 



they have been encouraged, there are few commons, no hedges, no 

 shepherds, no dogs to attend the flocks ; and the fences of wood and 

 stone are not sufficient to prevent active sheep from breaking pasture, 

 to the great destruction of adjacent crops. 



The advantage, however, in this respect, is counterbalanced by a 

 corresponding inconvenience arising from the same source, namely, 

 the great difficulty of driving such cripples to market, at the same 

 time that they are generally not so fat as others, from the greater 

 labour they undergo in gathering their food. 



These objections are indeed such, that since the introduction of 

 Merinoes, which are equally gregarious, quiet, and orderly, in ad- 

 dition to the strong recommendation of their fleeces, the ancon breed 

 appears in danger of becoming wholly extinct ; so that the author 

 had some difficulty in procuring one in Boston to be dissected, for the 

 purpose of sending a skeleton, which accompanied the letter, and 

 was laid before the Society. 



Experiments to ascertain the coagulating Power of the Secretion of the 

 gastric Glands. By Sir Everard Home, Bart. F.R.S. Communi- 

 cated by the Society for promoting the Knowledge of Animal Che- 

 mistry. Read January 21, 1813. [Phil Trans. 1813,^. 96.] 



It has long since been observed, that the first step in the process 

 of digestion is the conversion of the food into a jelly ; but whether 

 this is effected by means of the gastric liquor alone, or by a joint 

 operation of other secretions, has not been ascertained. From Mr. 

 Hunter's experiments, it appeared that the same species of coagu- 

 lation takes place in the same food admitted into the stomach of a 

 great variety of animals ; and that in the calf's stomach this power 

 resided in the fourth cavity alone ; since the mucus taken from the 

 surfaces of the first, second, or third cavities, had no such effect as 

 rennet, which is prepared by infusion of the inner membrane of the 

 fourth cavity. 



The same inquiry is here pursued by the author, with a view to 

 ascertain more accurately what part it is that possesses this property 

 in the highest degree, by comparison of the effects of rennet pre- 

 pared from different portions. 



By this mode of trial no part of the hog's stomach was found to 

 coagulate milk, but that near the pylorus, where the gastric glands 

 are situated. 



Experiments were next made with rennets prepared from the crop 

 and gizzard of a cock, from the stomach of a shark, the stomach of a 

 salmon, and that of a thornback, all of which had the power of coa- 

 gulating milk. 



Other experiments were afterwards made, with the assistance of 

 Mr. Hatchett and Mr. Brande, on the comparative powers of different 

 parts of the same stomach, and the difference in various species of 

 animals, the chicken, hawk, turkey, and calf. 



In a chicken the horny lining of the gizzard gave a firmer curd 



