What are some symbols in chapters 3 and 4 of Of Mice and Men?

Candy’s dog is a predominant symbol as individuals who are weak and considered useless by society. Once an excellent cattle dog, it is now toothless, smelly, and old. Candy has had it since it was a puppy, and he is reluctant to put it out of its misery, though Carlson points out that it would be a kindness.

The puppies are also a symbol of vulnerability. Candy is promised one to take the place of his dog, and Lennie is given one as well. Lennie likes to pet it, but he does not realize that it is weak and needs the protection of someone else, in this case its mother. Responding to a perceived aggression, Lennie smacks the puppy and kills it, much as he has done to the mice he has been given in the past. His fear of attack causes Lennie to strike back, which also leads to the death of Curley’s wife.

Both Candy’s dog and the puppy symbolize the position of those who are weak and vulnerable in society, such as Lennie. The world has no place for such individuals, and their death is the most likely solution seen by society.

What is an example of verbal irony and symbolism in Of Mice and Men, chapter 4?

Verbal irony is the use of words to convey a certain meaning that is the opposite of the literal or intended meaning. It is using vocabulary to describe something or express something in a manner that is other than it seems to be. 

Symbolism is the use of something physical or tangible to represent an idea or quality, metaphorically. 

One of the key symbols in this book that comes up again in Chapter 4 is the dream of owning a patch of land and living "on the fatta the lan'." This key image recurrs throughout the story and seduces not only George and Lennie but other characters too, such as Candy and Crooks. It is such an important symbol beause it symbolises dreams, freedom and independence in an otherwise cruel world.

Verbal irony is saying the opposite of what you really mean. We see an example of this when Candy enters Crooks' room and Crooks says:

"Come on in. If ever'body's comin' in, you might just as well."

Clearly this is ironic because Crooks is fiercely possessive of his space and does not like others invading it. On the other hand, inspite of the tone of voice, he is lonely and therefore wants company.