What passages in Harper Lee's To Kill a Mockingbird help develop the themes of maturation and loss of innocence?

In Harper Lee's To Kill a Mockingbird, Chapter 11 is one chapter full of passages concerning the themes of maturation and loss of innocence.

Scout opens this chapter by explaining how much she and Jem had grown since the start of the story. They had grown so much that they had set aside their desires to vex Boo Radley and instead became focused on wanting to venture into the business side of Maycomb, especially to meet their father on his way home from work. The difficulty is that they had to pass the house of Mrs. Henry Lafayette Dubose, recognized as the meanest old woman in town, to get to the business side of Maycomb. The very fact that they feel brave enough to attempt the journey shows us how much they have grown, for, as Scout narrates, "Previous minor encounters with her left me with no desire for more, but Jem said I had to grow up some time" (Ch. 11).

Passages concerning Jem particularly capture the themes of maturation and loss of innocence. With each passing day, based on his father's advice, Jem is able to accept like a gentleman the insults Mrs. Dubose hurls at the children as they walk past, with his head held high, showing his maturity. However, Jem goes berserk the day Mrs. Dubose makes the racist comment, "Your father's no better than the niggers and trash he works for!" (Ch. 11). Mrs. Dubose's racist comment serves to show just how much Scout and Jem are being subjected to the evils of the world, such as racism, which shows they are losing their innocence. In response to her racist insult of his father, Jem whacks off every white camellia flower in Mrs. Dubose's garden, a retaliation that further shows just how much Jem is losing his innocence.

The aftermath of Jem's deed further develops the theme of maturation. Jem is sent to Mrs. Dubose's to apologize, who asks Jem to start coming to her home every day to read to her. Jem shows a great deal of bravery in reading to the ill Mrs. Dubose, who undergoes a series of physical fits each time he is there. Finally, upon her death, Atticus makes the surprising statement that he saw Mrs. Dubose as a "great lady" and the "bravest person [he] ever knew" (Ch. 11). As Atticus explains to Jem, Mrs. Dubose had been a morphine addict because she had been prescribed morphine for years to treat the pain from her sickness. Though taking morphine was justifiable, Mrs. Dubose decided that she wanted to die free of the addiction because she wanted to "leave this world beholden to nothing and nobody"; therefore, she had asked Jem to read to her to help distract her from her pain and withdrawal symptoms. Due to Atticus's explanation, soon, Jem is able to see Mrs. Dubose as not just a mean old lady but as a very brave person whose bravery is worth emulating, showing us just how much Jem matured from his experience with her.