Why is it that nervous system is compared to an airmail delivery while the endocrine system to the pony express?

What cranial nerve is used for chewing food? How do cells work together to form tissues? What was the purpose of Mendel's experiments with dihybrid crosses? What term is used to refer to the breeding of improved varieties of plants and animals? What is information which is numerical? Where does a plant get its energy for photosynthesis and what is the energy transformed into after photosynthesis is complete? Do the bronchioles have cartilage support? Organ systems can be composed of cells or tissues but not both? Where is the red blood cell made in the body? What are example of microbial ammensalism? Do skeletal muscles continue to contract following death? Why nut can go into the right main bronchus instead of left main bronchus? The shoulder girdle is made up of the clavicle and what other bone? Does Gatorade make your bones weaker or affect them in any way? What are the four major parts of the hindbrain? What is the main part of are body which is attached to our legs and arms called? Why is the E. coli lac Z gene used as a reporter gene in S. cerevisiae cells but not in E. coli cells? Why is the structure important for the function in cell membrane? Should chemical pesticides be banned? What is the reaction due to reaction from stimulus?

Why is it that nervous system is compared to an airmail delivery while the endocrine system to the pony express?