Experimental studies have been made of the influence of the wake amine in vitro on the decomposition of the five enzymes, namely, pepsin, trypsin, lipase and amylase, and further, the urease which is one type of amidase supposedly related with the gastric acidity, and the results obtained was summarized as follows. 1. The Influence of Hospitan or Zedrin on the decomposing action of pepsin and trypsin on casein in lower concentration (terminal concentration 8.3 × 10(-5) M) could hardly be seen but in higher concentration (terminal concentration 8.3 × 10(-4) M to 8.3 × 10(-2) M), the decomposing action of both enzyms were definitely lowered. 2. That the infenence of Hospitan or Zedrin on decomposing action of lipase on olive oil was not marked in lower concentration (terminal concentration 1.66 × 10(-4) M), but in higher concentration, (terminal concentration 1.66 × 10(-3) M to 1.66 × 10(-1) M). The decomposing action of lipase does steadily lowered as the concentration enhanced. 3. The influence of Hospitan or Zedrin on the glucolysis of amylase was practically none in lower concentration (terminal concentration 8.33 × 10(-5) M), but in higher concentration (termnial concentration 8.33 × 10(-4) M to 8.33 × 10(-2) M), the glycolytic action of amylase is definitely lowered. 4. The influence of Hospitan or Zedrin on the decomposing action of urease was hardly be seen in lower concentration (terminal concentration 9.1 × 10(-5) M), but in higher concentration (terminal concentration 9.1 × 10(-4) M to 9.1 × 10(-2) M) the decomposing action of urease is apparently increased.