It looks like you may be referring to the theme of racism in Chapter 1. Chapter 2 does not appear to include any clear examples of racism.
In Chapter 1, the theme of racism is demonstrated by the doctor's attitude and how the villagers accept without question the divide between the races. The author uses the setting, dialogue, and inter-racial conflict to develop the theme of racism in Chapter 1. When Kino and Juana call for the doctor to attend their baby, Coyotito, the doctor refuses to show up. The people repetitively saying "he would not come" reinforces the idea of a divide between the two groups.
Because the doctor will not come to them, Juana and Kino decide that they will go to him. The text tells us that the excursion becomes a "neighborhood affair." When the villagers reach the city, it looks phenomenally different from the neighborhood they have just left. The author contrasts the setting of both neighborhoods by using visual imagery. While the villagers live in brush houses, the people in the city live in buildings of "stone and plaster." There are beautiful gardens in the city, and bougainvillaea crest the walls of buildings.
The author further develops the theme of racism by drawing attention to the conflict between the rich and the poor. The doctor is presumably white and comes from a race of people "which for nearly four hundred years had beaten and starved and robbed and despised Kino's race." The author highlights the conflict between the two races by revealing the internal thoughts of one of the characters.
And as always when he came near to one of this race, Kino felt weak and afraid and angry at the same time. Rage and terror went together. He could kill the doctor more easily than he could talk to him, for all of the doctor's race spoke to all of Kino's race as though they were simple animals.
In the end, the doctor refuses to attend to Coyotito. Kino's seed pearls are described as "ugly and gray as little ulcers, flattened and almost valueless." Because of Kino's poverty and inability to pay, the doctor refuses to treat the baby. The author definitely uses the setting, dialogue, and inter-racial conflict to develop the theme of racism in Chapter 1.