What is the legal status of an agent appointed by an agent when the principal explicitly authorized the agent to appoint a substitute for himself?

Primary text

If the principal permits the agent to appoint a substitute for himself (meaning the substitute acts on behalf of the first agent), the substitute becomes an agent of the original principal. This substituted agent is dismissed upon the death or dismissal of the first agent. If the original principal dies or dismisses the first agent, both the first and second agents are simultaneously dismissed because both derive their authority from the original principal.