Ptyalin is a starch digesting …………………………… , secreted by …………………………… gland.

Explanation

**Step-by-Step Solution:**

1. **Identify the Function of Ptyalin:**
- Ptyalin is known as an enzyme that digests starch. Its primary role is to break down starch into simpler sugars.

2. **Determine the Type of Substance:**
- Since ptyalin is involved in the digestion of starch, it is classified as a starch-digesting enzyme.

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