With Automated Emails in Campaigns, the second and subsequent touches would not include the previous communication as inline/quoted text. If you would like the previous messages to be included in subsequent Automated Email touches, you may want to include it within the message body for each follow up email in the Campaign sequence.
If you are using Manual Email touches, the previous email message will likely be quoted in the reply. This depends on the behavior of your email client, yet Gmail will do this by default.
The messages should be threaded or show in "conversation view" if they contain the same subject line and if "conversation view" is turned on in your email client.
You can learn more about the Campaign feature here.