Where a land owner authorized a person to write to an agent authorizing him to sell real estate, which the agent does pursuant to the letter so written, after which the land owner disputes his authority to sell, an instruction that a delegated authority to an agent to sell real estate can not be re-delegated, is misleading and erroneous. Gross v. Schafer, 29 Kan. 442. See Sec. 5 for acts which can not be sub-delegated.