APPARATUS FOR PHYSIOLOGICAL USE. 



into small pieces, or to chop up a piece of pancreas and 

 soak the fragments in alcohol for a few days, so as to 

 coagulate the albumen. You then pour off the alcohol and 

 pour on some glycerine, and allow it to stand. The 

 glycerine dissolves the different ferments, and the albumen 

 having been previously coagulated, you get a solution of the 

 ferment tolerably free from albuminous matters. You can 

 also buy the ferments of the stomach and pancreas. The 

 substance sold as pepsin is obtained by simply scraping 

 the mucous membrane of the stomach and drying it. ] I do 

 not know how the preparation from the pancreas is made, 

 but both of these are most efficient ; and it saves you the 

 trouble of making them for yourselves. These ferments 

 which exist in the body vary in their character. The first 

 we meet with in passing down the alimentary canal is the 

 ferment of the salivary glands. The action of this you 

 can readily ascertain by simply chewing a piece of bread. 

 It soon gets sweet, showing that the starch of the bread is 

 becoming converted into sugar. The second is pepsin, 

 the ferment of the stomach. This only acts in an acid 

 solution. Here are two pieces of fibrine, which I put into 

 these two flasks at the beginning of the lecture, and which 

 have been kept at blood-heat in the water-bath. Both of 

 them were treated with dilute hydrochloric acid, but to one 

 of them a little powdered pepsin was also added. You 

 see that the hydrochloric acid alone has simply caused the 

 fibrine to swell up. But the hydrochloric acid and pepsin 

 together have had a very different action. They have 

 almost completely dissolved the fibrine. The solid parts 

 have almost entirely disappeared, and the whole of it is dis- 

 solved just as it would have been in an animal's stomach. I 

 might have treated a third piece of fibrine with water and 

 pepsin alone for the sake of comparison, but it would 

 have been of no use, except to show you that pepsin has 

 no action whatever. You would have found that the fibrine 

 remained exactly as it was before. 



The next ferment is that from the pancreas, which has 

 a threefold action. Like pepsin it dissolves fibrine, but it 



1 Pepsin may be obtained from Messrs. Bullock and Key n olds, 

 Hanover Street, Hanover Square, London, and pancreatine from Messrs. 

 Savory and Moore, Bond Street, London. 



