Number of cocoons formed after each mating in pheretima are 

Options

A. one cocoon
B. many cocoons are formed at a time
C. many cocoons are formed in succession
D. four cocoons

Answer

To determine the number of cocoons formed after each mating in Pheretima, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Pheretima**: Pheretima is a genus of earthworms, and we need to focus on their reproductive process, particularly after mating.

2. **Mating and Ovary Maturation**: After mating, the ovaries of the Pheretima mature. This maturation is crucial for the formation of cocoons.

3. **Cocoon Formation Process**:
- After copulation, a membrane is secreted around the clitellum (a thickened, glandular section of the body).
- This membrane moves towards the anterior vent (the front opening) while the womb starts to withdraw backward.

4. **Reception of Ova and Sperm**: During this process, the membrane receives ova (eggs) from the female genital aperture and sperm from the male.

5. **Cocoon Structure**: Once the membrane is laid on the ground, it closes at the elastic opening, forming a structure known as a cocoon.

6. **Fertilization**: Inside the cocoon, one sperm fertilizes one ovum to form a zygote, which will develop into a young worm.

7. **Number of Cocoons**: The key point is that many cocoons are formed in succession after each mating, rather than just one or a fixed number.

8. **Conclusion**: Therefore, the correct answer to the question is that many cocoons are formed in succession after each mating in Pheretima.

### Final Answer:
**Many cocoons are formed in succession after each mating in Pheretima.** (Option C)