LECITHIN. 2 1 
Lecithin is a complex fat of wide distribution. It is a constant 
constituent of protoplasm, and is found both in the animal and 
vegetable 1 world. In I he animal tissues, it is found principally in 
the brain and nervous tissues, where it is probably a decomposition 
product of a more complex substance originally called protagon by 
Liebreich 2 (see section on "Chemistry of Nervous Tissues"); in yolk 
of egg; 3 and in blood corpuscles. 4 Lecithin is found in all organs 
composed of cells, and also in certain secretions, namely, semen, bile, 
and milk. 
Lecithin is a yellowish white, waxy, hygroscopic solid, soluble in 
ether and in alcohol ; it swells and forms a kind of emulsion with 
water. When ignited it burns and leaves a residue of metaphosphoric 
acid. Its most important compounds are those of its hydrochloride 
with platinum chloride (C\ 4 H 90 lSrPO y Cl) 2 +PtCl.,, and with cadmium 
chloride which has a corresponding formula. 5 
Montgomery 6 showed that when water, glycerin, and other reagents 
were added on a microscopic slide to impure lecithin (or protagon, as he 
termed it), prepared from egg-yolk, snake-like forms shoot out, bending 
and curling and even simulating nerve fibres or nerve cells. On 
cooling a solution of lecithin in alcohol, it separates out in crystal- 
line clumps. On decomposition by alkalis, it yields glycero-phosphoric 
acid, a fatty acid, and an alkaloid choline. 
Choline is an ammonium base, and has the following constitution: — 
f(CH 3 ) 3 ) 
N CH„— CH,OH \ = C 5 H 16 NO„ 
lOH J 
It is therefore trimethyl-oxyethyl-ammonium hydroxide; its name 
is derived from the fact that it was first separated from the lecithin of 
the bile. Its synthesis was accomplished by Wurtz? from ethylene 
tetronerythrin — Wurm, Ztschr. f. wissensch. Zool., Leipzig, 1871, Bd. xxxi. S. 535 ; 
Merejkowski, Compt. rend. Acad. d. se., Paris, 1881, tome xciii. p. 1029 ; MacMunn, Proc. 
Birmingham Phil. Soc, vol. iii. p. 351 ; Proc. Hoy. Soc. London, 1883, No. 226, p. 17 ; 
Halliburton, Journ. Physiol., Cambridge and London, 1884, vol. vi. p. 324; Krukenberg, 
Centrctfbl. f. d. Tried. Wissensch., Berlin, 1879, Bd. ix. S. 705. On serum lutein— 
Krukenberg, Sitzwngsb. d. Jenaisch. Gcsellsch.f. Med. u. Xaturw., 1885; Halliburton, Journ. 
Physiol., Cambridge and London, 1885, vol. vii. p. 324. On saponification of lipochromes 
— Kiihne, loc. cit. ; Maly, Monatsh. d. ''Item., Wien, 1881, Bd. ii. S. 351 ; Bein, Per. d. 
deutsch. chem. Cfesellsch.] Berlin, 1890, Bd. xxiii. S. 204. On carrotin — Husemann, Ann. d. 
chem., Leipzig, Bd. cxvii. S. 200; Arnaud, Compt. rend. Acad. d. se., Paris, tome cii. 
p. 119; civ. 1293. Newbiggin, "On Crustacean Pigments," Journ. Physiol., Cambridge 
and London, 1897, vol. xxi. p. 237. 
1 On the subject of lecithin and choline in vegetable oils, etc., see Heckel and 
Schlagdenhauffen, Compt. rend. Acad. d. se., Paris, tome ciii. p. 188 ; Jacobson, Ztschr. f. 
physiol. Chem., Strassburg, Bd. xxiii. S. 33; Sehulze, ibid., Bde. xi. S. 3G5 ; xii. S. 441 ; 
xvii. S. 204 ; J. Stoklasa, Per. d. deutsch. chem. Gescllsch., Berlin, 1896, Bd. xxix. S. 2761. 
2 Ann. d. Chem., Leipzig, Bd. exxxiv. S. 29. 
3 Gobley, Journ. de pharm. et ehim., Paris, tomes xi., xii.. xvii., xviii. ; Parke, 
Hoppe-Seyler's "Med. Chem. Untersueh.," Berlin, Heft 2. S. 213 ; Hoppe-Seyler, ibid., S. 
215 ; Diaconow. ibid., S. 221 ; Ccnlralbl. f. d. med. Wissensch., Berlin, 1S68, S. 2. 
4 Gobley, Journ. de pharm. et chim., Paris, tome xxi. p. 250; Hermann, Arch, 
f. Anat. u. Physiol., Leipzig, 1866, S. 33; Hoppe-Seyler, "Med. Chem. Untersueh.," Berlin, 
Heft 1, S. 140 ; Jiidell, ibid., Heft 3, S. 386. 
3 The formation of these compounds enables one to prepare lecithin in a pure form, the 
metal being subsequently got rid of by sulphuretted hydrogen. 
6 "On the Formation of So-called Cells," London, 1867. 
1 Ann. d. Chem., Leipzig, 1868, Supplement, Bd. vi. S. 116 and 197 ; see also Bayer, 
ibid., Bd. cxl. S. 306, 
