86 CHEMICAL COMPOSITION OF THE BODY. 



it is precipitated by corrosive sublimate and by neutral acetate of lead. Oil 

 boiling with sulphuric acid, it yields leucin and tyrosin. 



ELASTIN is characterized by its stability and insolubility. It yields no 

 gehitin even on protracted boiling in water, and is not acted on by acetic 

 acid. It is, however, dissolved by boiling alkalies and by sulphuric acid at 

 ordinary temperature, which at last decomposes it; giving rise to leuciu. 

 Nitric acid gradually dissolves it with the xantho-proteinic reaction. It is 

 obtained in an almost pure state from the ligameutum iiuchre, but is gener- 

 ally associated with much connective tissue. 



GLOBULIN or CRYSTALLIN is obtained from the crystalline lens. It dis- 

 solves in acetic acid, but it is precipitated by exact neutralization with 

 ammonia, and vice versa, it is dissolved by ammonia, but is precipitated by 

 exact neutralization with acetic acid. It is completely precipitated from its 

 solutions by carbonic acid. 



HEMOGLOBIN, H.EMATOCRYSTALLIN, a coloring substance closely allied 

 to the albuminous compounds will be fully described iu the chapter on the 

 blood. 



Nrt.'Li-:iN has been obtained by Miescher from the nuclei of lymph-cor- 

 puscles. It is soluble in alkalies and in alkaline bicarbouates, and is pre- 

 cipitated again by acids. 



CEREBRIN, Cj 7 H, :! NO s , is a white powder which can be obtained from the 

 nervous and some other tissues ; it is soluble in warm ether and alcohol, but 

 insoluble in water and in ammonia. It swells up remarkably iu cold water. 

 When boiled with acids it yields a kind of sugar, and is, therefore, a gly- 

 coside. 1 \ 



PEPTONE, METAPEPTONE. These terms are applied to the substances 

 resulting from the action of gastric juice on the various albuminous com- 

 pounds, which they resemble in some points but differ from in others. They 

 are yellowish-white, amorphous, and hydroscopic bodies, soluble in water, 

 not precipitated by heat nor by potassium ferrocyanide. They are precipi- 

 tated by tanuic acid, iodide of mercury-potassium, nitrate of silver, corrosive- 

 sublimate, and, when added in large excess, by alcohol. They rotate the 

 plane of polarized light to the left. They are crystalloids, diffusing easily 

 through animal and vegetable membranes. Peptone-like bodies are pro- 

 duced by the action of ozone and of protracted boiling in water, or albumen. 



LECITHIN is an imperfectly crystalline body resembling wax, easily fusible 

 and soluble in hot alcohol and ether, and forming combinations with acids 

 and salts. In warm water it swells up like cerebrin. It is very unstable. 

 After protracted boiling with alcohol, and more easily on the addition of 



f (~)fT 



acids or alkalies, it breaks up into Neurin (Cholin) C. 2 H 4 - ]si ( nfr \ OH- 



palmitic and oleic acids, and into glycerin-phosphoric acid. Its formula is 

 very complicated, being thus given by Frey : 



0. C I H0 

 O. C i 



( Y' Yl6 "31 



r< TT l vy. v^ 18 xi 3S w 

 (OH 



5 |O.PO 



0. C,H/CH,) 3 N. OH 



Besides being a constituent of the nervous system, Lecithin occurs in the 

 yolk oi' the foul's egg, in the blood-corpuscles, bile, semen, and pus; accord- 

 ing to Datrilewsky 2 it is generated in muscular tissues during tetanus. 



1 See I >i:<rc >im\v, (Vntr.-ilblatt. 18(58, p. 3. Strecker, Zeitschrift 1'iir Cheinic, 1868, 

 ji. -l:;7; iiml Frcy, 1 1 i-tnrhrmir, 1873, p. 29. 



2 Centralblatt, 187^, p. 433. 



