138 CEREBRIK CHARCOT'S CRYSTALS. 



decomposed, yielding the several products which result from the 

 decomposition of lecithin under the same conditions, together with 

 an additional product known as cerebrin. 



Cerebrin. 1 C n H 88 N0 8 (?). 



Is found in nerves, in pus corpuscles, and largely in the brain. 

 In former times many names were given to the substance when in 

 an impure state, ex.gr. cerebric acid, cerebrote, &c. It was first 

 prepared by W. Miiller 2 who constructed the above formula from 

 his analysis; the mean of these is C, 6845. H, 11-2. N, 4-5. 

 O, 15 '85. Great doubts are however thrown upon the purity of 

 Miiller's preparations by the researches of later observers. From 

 a later investigation it appears to contain less nitrogen than is 

 stated above, the carbon and hydrogen beirig the same (C, 68 '74. 

 H, 10-91. N, 1-44. O, 18-91). 3 



It is prepared from brain substance by extraction with alcohol 

 and purified by recrystallisation from this solvent ; its complete 

 separation however from lecithin &c. is difficult, but is attained 

 by treating the mixture with boiling barium hydrate : this, while 

 it has no effect on the cerebrin, decomposes the lecithin. 



It is a light, colourless, exceedingly hygroscopic powder, which 

 swells up strongly in water, slowly in the cold, rapidly on heating. 

 When heated to 80 it turns brown, and at a somewhat higher 

 temperature melts, bubbles up, and finally burns away. It is in- 

 soluble in cold alcohol, or ether ; warm alcohol dissolves it readily. 

 Heated with dilute mineral acids, cerebrin yields a sugar which 

 has recently been shown to be identical with galactose. (See 

 above p. 106.) 



Charcot's Crystals. 



These remarkable crystals, whose chemical nature and signifi- 

 cance have been the subject of much surmise, were first described 

 by Charcot 4 in the spleen and blood of leukhaemic patients. 

 Later researches have confirmed their characteristic appearance in 

 this disease, and have further shown that they occur in health, 

 more particularly in semen, but also in various tissues ; 6 they are 

 also found in asthmatic expectorations. They may be readily 

 obtained from semen by extracting with warm water, to which a 

 little ammonia had been added, the residue which remains after 



1 See Gamgee, Physwl. Chem. Vol. i. p. 439. 



2 Ann. d. Chem. u. Phai-m. Bd. cv. (1858), S. 361. 



8 Geoghegan, Zi. f. physiol. Chem. Bd. in. (1879), S. 332. See also Parcus, Jn. 

 f. prakt. Chem. (N.F.) Bd. xxiv. (1881), S. 310. 



* Compt. Rend. Soc. Biol., 1853. Gaz. Hebd. I860, p. 755. 



5 Zenker, Arch. f. klin. Med. Bd. xvnr. (1876), S. 125. Schreiner, Ann. d. 

 Chem. u. Pharm. Bd. 194 (1878), S. 68. Cf. Maly's Jahresb. iiber Thierchemie, 

 1878, S. 86. 



