Explain the process of mating and the formation of the cocoon in earthworms.

(N/A) $1$. Mating: Earthworms are hermaphrodites,but they perform cross-fertilization. During mating,two earthworms come in contact with each other,facing opposite directions,such that the male genital pores of one worm come in contact with the spermathecal pores of the other.
$2$. Sperm Exchange: Sperms are exchanged between the two worms and are stored in the spermathecae of the partner.
$3$. Cocoon Formation: After mating,the glandular cells of the clitellum secrete a mucous-like substance that forms a girdle or cocoon around the clitellar segments. As the worm moves forward,this cocoon slides over the anterior segments,collecting eggs from the female genital pores and sperms from the spermathecae (which were received during mating).
$4$. Fertilization: Fertilization and development occur within the cocoon,which is then deposited in the soil.