275 
free agar, nay in some experiments the protein-free agar had become 
so soft that it could not be divided into three small cylinders so 
that comparison with the protein-containing agar was impossible. 
In accordance with this we also found, that the enzyme proceeds 
in agar with casein more rapidly in acid-, than in neutral reaction. 
A 3°/, neutral solution was made of pure casein prepared after 
HAMMARSTEN by addition of NaHO. A part of this was diluted with 
an equal volume of water, another part with an equal volume of 
0.4°/, HCl. The precipitate arising primarily on the addition of 
hydrochloric acid was dissolved again in the excess of acid. 
Of this neutral solution 5 CC was put in two tnbes filled with 
pepsin-agar, and was mixed with 5 CC 3°/, agar. In two other 
tubes 5 CC of the acid solution mixed with 5 CC 3°/, agar. 
After 3 days: 
‘Weight Clotting |Colorim.| Weight | Clotting |Colorim.| Weight |Clotting | Colorim. 
4 ; not meas- 
acid I 2.27 | 3 min 4.5 II 2.30 | none 0.6 Ill 2.24} none cable 
neutral 12525" ANR 5.6 II 2.30 | none 0.3 III 2.30} none 0 
After 4 days: . 
acid I 2.32 |1!/, min. 4.4 II 2.30 | 10 min.) 1.6 I. 2.33) 13 min. 1.3 
neutral | BAE U WES 4.2 II 2.33 | none 0.3 II 2.30) none 0 
In both sets of tubes, then, there was a balance in favour of the 
acid solution. After 4 days pepsin could even distinctly be observed 
in the top cylinder of the acid gel. 
Also with a neutral reaction the movement of the enzyme through 
the gel was aided by the presence of protein, as appeared from an 
experiment with milk. 
Of 4 tubes containing pepsin-agar two were supplied with 3 CC 
milk mixed with 7 CC 3°/, agar; the other two with 3 CC 1°/, NaCl 
mixed with 3 drops of 1°/, CaCl, and 7 CC 3°/, agar. 
We observed that also globulin from blood-serum and from edestin 
had a favourable action on the movement of pepsin through the 
agar-gel. 
Finally [ report some more experiments which I carried out to 
verify the supposition from which I started, viz. that the advance of 
the pepsin in the protein-containing gel is promoted, because besides 
