ADP --> ||
COOH
+------+ | +---+
|CO_{2}| + CH_3CHO <-------- C=O + |ATP|
+------+ acetaldehyde | +---+
carbon | CH_{3}
dioxide | + dihydro-coenzyme pyruvic acid
|
v
+----------------+
| CH_{3}CH_{2}OH | + coenzyme
+----------------+
ethyl alcohol

[Illustration: Figure 13.--SURVEY OF ALCOHOLIC FERMENTATION, 1951. The
"well-known scheme of alcoholic fermentation" according to Albert Jan
Kluyver (1888-1956), presented before the Society of Chemical Industry
in the Royal Institution, March 7, 1951. In _Chemistry & Industry_,
1952, page 136 ff., Kluyver restates that "... the fermentation of one
molecule of glucose is indissolubly connected with the formation of two
molecules of adenosine triphosphate (ATP) out of two molecules of
adenosine diphosphate (ADP)."]

Shortly after this experience had been gained, it became valuable for
understanding the chemical nature of a new substance extracted from a
natural organ. This substance was named lecithin by its discoverer,
Nicolas Theodore Gobley[27] (1811-1876), because he obtained it from egg
yolk (in Greek, _lekidos_). He used ether and alcohol for this
extraction. Had he used water and mineral acid instead, he would not
have found lecithin, but only its components. As Gobley and, slightly
later, Oscar Liebreich (1839-1908), subjected lecithin to treatment with
boiling water and acid, they separated it into three parts. One of them
was the glycerophosphoric acid of Pelouze, the second was the well-known
stearic acid of Chevreul, but the third was somewhat mysterious. This
third substance was the same as one previously noticed when nerves had
been subjected to an extraction by boiling water and acid and,
therefore, called nerve-substance or neurine. Adolf Friedrich Strecker
(1822-1871) established the identity of this neurine with a product he
had extracted from bile and which went under the name of choline.
Adolphe Wurtz (1817-1884) succeeded in synthesizing this substance from
ethylene oxide, CH_2.O.CH_2 and trimethylamine N(CH_3)_3.[28] Thus, all
three parts were identified, and Strecker put them together to constr