A convenient apparatus for the determination of ferment action.

Abstract

In determinations of ferment action it is first of importance, that both ferment and substrate be brought to the same temperature before mixing. Secondly, the mixing of any series of tubes containing ferment and substrate should be carried out simultaneously. For this purpose, a test tube with a side arm (see figure) was constructed, so that (a) could contain the substrate and (b) the ferment. A series of these tubes is filled with the appropriate solutions, and placed in the holder (c), which enables one to handle the entire series of tubes while in the water bath. When the desired temperature has been attained, the two components in every tube may be mixed at once by simply rotating the handle of (c).

In certain methods it is of importance that the non-digested substrate in the entire series of tubes be precipitated at the same time. The parts (d, e, f) are available for this purpose. Through the opening in (e) a sufficient amount of the precipitating-fluid is introduced with a pipette into the trap-tube (d) after which the openings in (e) are tightly stoppered. The end of tube (d) is introduced into the mouth of the test tube (a, b). At the appropriate time, pressure on the bulb (f), immediately followed by rotation of the handle (c), will effect immediate and simultaneous precipitation in all tubes.

In determinations of the trypsin-inhibiting power of serum the v. Bergmann-Gross-Fuld Method 1 , 2 it is important that the trypsin should be placed in one limb of the test tube (a, b) and the substrate and serum in the other; if trypsin and serum are at first placed together, large errors may ensue in consequence of the trypsin being “fixed” by the serum in amounts depending upon the length of time during which the two substances are in contact before exposure to the substrate.