………… operates on the principle of haemodialysis.

Explanation

**Step-by-Step Solution:**

1. **Understanding Hemodialysis**: Hemodialysis is a medical procedure used for patients whose kidneys are unable to filter waste products from the blood effectively. It is a crucial treatment for those with kidney failure.

2. **Function of the Kidneys**: The primary role of the kidneys is to filter waste materials from the blood and excrete them through urine. When kidneys fail, waste accumulates in the bloodstream, necessitating alternative methods of filtration.

3. **Artificial Kidney**: In hemodialysis, an artificial kidney, known as a dialyzer, is used. This device mimics the filtering function of healthy kidneys.

...