378 PREPARA TION- OF PEPSIN'. 



performance, and the results uncertain, and partly 

 from the sale of perfectly useless preparations, the 

 remedy has to some extent lost its reputation. Many 

 years ago (1854) when engaged upon some experi- 

 ments on artificial digestion, and after having met with 

 considerable difficulty in obtaining clear solutions that 

 would filter, I tried various new plans of preparing 

 digestive fluids ; and from the circumstance that the 

 pig was an omnivorous animal, with a very strong 

 digestion, and his stomach to be easily procured for a 

 small sum, I was led to try his pepsin in preference to 

 that of any other animal. The following mode of 

 preparation was found to answer very satisfactorily. 

 It is free from many of the objections to which other 

 processes are liable. 



The mucous membrane of a perfectly fresh pig's 

 stomach was carefully dissected from the muscular 

 coat, and placed on a flat board. It was then lightly 

 cleansed with a sponge and a little water, and much 

 of the mucus, remains of food, etc., carefully removed. 

 With the .back of a knife, or with an ivory paper- 

 knife, the surface was scraped very hard, in order 

 that the glands might be squeezed and their contents 

 pressed out. The viscid mucus thus obtained contains 

 the pure gastric juice with much epithelium from the 

 glands and surface of the mucous membrane. It is to 

 be spread out upon a piece of glass, so as to form a 

 very thin layer, which is to be dried at a temperature 

 of 1 00 over hot water, or in vacuo over sulphuric acid, 



