326 
CHEMISTRY OF THE DIGESTIVE PROCESSES. 
oil of almonds, 5 parts of gum-arabic, and 35 parts of water. A solution 
of litmus is prepared of such concentration and reaction that it shows a violet 
colour when placed in test tubes about a centimetre in diameter in front 
of white paper; in each test tube 10 c.c, of this dilute litmus solution are 
placed ; to each five drops of emulsion are added ; then equal volumes of each 
of the pancreatic extracts to be compared. From the times in which an equal 
amount of red develops in the litmus in each case, the richness of the extracts 
in fat- splitting ferment may be determined. Or a series of determinations 
for each extract, using a varying quantity of it, may be made, and the 
members of each series compared. 
The condition of the material to be digested has also a profound 
effect upon the rapidity. The factors of most moment are — 
1. Whether the material is fluid or solid. 
2. Whether it has previously been heated (cooked) or not. In the 
case of starch, previous heating and formation of a starch paste shortens 
the process in the ratio of hours to minutes ; in the case of proteids, 
previous heat coagulation slows the after process of digestion. 
3. Materials which must first be dissolved, and must therefore he 
attacked from the outside, are digested more quickly when in a finely 
subdivided condition. 
Classification of Enzymes. 
Class of Enzyme. 
-, , ,, Digestive Fluid in 
Name of Enzyme. which found. 
Concise Description of 
Specific Action. 
Diastatic . . - 
1. Ptyalin 
2. Amylopsin 
Saliva 
Pancreatic juice 
Convert amyloses 
(starches and glyco- 
gen) into dextrins, 
maltose, and isomal- 
tose, accompanied by 
a trace of glucose. 
Proteolytic . . * 
1. Pepsin 
2. Trypsin 
( tastric juice 
Pancreatic juice 
Converts proteids into 
albmnoses and pep- 
tones. 
Converts proteids into 
albumoses, peptones, 
and amido-acids. 
Fat-splitting or 
steatolytic 
Steapsin or 
pialyn 
Pancreatic juice 
Splits up neutral fats 
into fatty acids and 
glycerin. 
Coagulating . . 
1. Rennin 
2. An unnamed 
ferment occur- 
ring in pan- 
creatic juice, 
which also 
coagu 1 a te s 
milk 
( Jastric juice 
Coagulates milk, con- 
verting caseinogen in 
presence of calcium 
salts into casein. 
