Schulze and Steiger isolated arginine from etiolated lupin seedlings in 1886. Koga and Otake isolated citrulline from watermelon juice in 1914. Wada gave it a formula in 1930 and kept the name from Citrullus. For a long time citrulline was an intermediate in the urea cycle, a way to throw ammonia out. Arginine was a building block. Then the vessel got involved.
A gas nobody expected
In the 1980s, Robert Furchgott found that the lining of a blood vessel released something that relaxed the muscle around it. The something was nitric oxide. Arginine is the substrate. Citrulline is the by-product, and then, in the kidney, a way back to arginine. Ignarro, Murad, Furchgott: the Nobel in 1998, for a gas that lasts seconds and opens a vessel. The gym heard "pump". The older job is simpler: blood flow.
Why the pair is split
Swallow arginine and the gut's arginase eats a lot of it before it arrives. Swallow citrulline and it slips past, becomes arginine in the kidney, and raises the pool more honestly. Schwedhelm showed the oral difference. So Jingfu, which is for the hour, keeps three hundred milligrams of arginine with muira puama and catuaba: a direct, when-needed stack. Qifu, which is for the week, keeps citrulline at five hundred milligrams a day: the slower door to the same pathway. We do not put both in both. That would be a catalogue, not a brief.
Nitric oxide is not a vitamin. It is a signal. These two amino acids are how we feed that signal without pretending a sachet is a prescription. Magnesium stays in Weifu and Changfu. B6 stays in Weifu. They support. They are not this plate.
Why they close Volume II
Volume I was the plants. Volume II is the bench: the eighth metal, the neglected borate, the bottled sun, and this pair from a seedling and a fruit. Jingfu and Qifu both need flow. They just do not need it at the same speed.
This volume keeps the salts. History first. The formula second. Claims last, and only the ones we can stand behind.
End of plate IV. End of Volume II.