The answer would have to be Melting Temperature. The reason being that, though colour, texture and even striations are all the way outermost physical aspects, thus can be seen, recognized and felt almost instantly, however the Melting Temperature is different because you can only acquire the definite measurement of it through a test or a series of different tests.
The Endocrine System. As noted earlier, the endocrine system is not a part of the nervous system, but it is still essential to communication throughout the body. This system is composed of glands, which secrete chemical messengers known as hormones.
Answer:
Warm air rises at the equator and moves toward the poles. At the poles, the cooler air sinks and moves back toward the equator.
Water soluble hormones affect target cells by binding to Plasma membrane receptor. The cell surface receptor is the binding site for water soluble hormones.The water soluble hormones must bind to binding site (cell surface receptor) because they are unable pass through plasma membrane freely due to their polarity.