CHEMICAL BASIS OF THE ANIMAL BODY. 133 



Cholesteriu is characterised, apart from its crystalline form, l>y 

 some striking reactions which may be obtained even with micro- 

 scopic quantities. 



(i) When the crystals are treated with concentrated sulphuric 

 add they usually turn violet or red. On the addition of a little 

 iodine the play of colours is very marked, the crystals being vari- 

 ously coloured, blue, red, green, violet. 1 



(ii) When dissolved in chloroform, the solution turns blood- 

 red on the addition of an equal volume of concentrated sulphuric 

 acid : this turns to blue, green, and finally yellow, the. change of 

 colour being very rapid if the solution is freely exposed to the air 

 in an open dish. The sulphuric acid under the chloroform exhibits 

 a green fluorescence. 2 



(iii) When evaporated to dryness on porcelain with a few drops 

 of concentrated nitric acid, a yellow residue is obtained, which 

 turns red if treated, while still hot, with ammonia. 



COMPLEX NITROGENOUS FATS AND THEIR DERIVATIVES.* 

 Lecithin. C^ 



Occurs widely spread throughout the body. Blood (red-cor- 

 puscles), 4 bile, and serous fluids contain it in small quantities, 

 while it is a conspicuous component of the brain, nerves, yolk 

 of egg, semen, pus, white blood-corpuscles, and the electrical 

 organs of the ray. It occurs also in yeast 6 and other vegetable 

 cells, and in small amount in milk. 6 



Tin- presence of lecithin in the red blood-corpuscles may prove to 

 be of no inconsiderable importance in connection with the possible 

 fixation liy them of carbonic anhydride. 7 Setschenow has shown that 

 lecithin :u-t- like a base towards carbonic anhydride, each molecule of 

 the suli-taiH being able to combine loosely with approximately one 

 molecule of the anhydride (-092 gr. lecithin fixes 2'7 cc. of CO,) 

 at a partial pressure of 56mm. 8 Further, it is stated that red M ..... 1- 



I figures in Fi-.nkc. Atlas d. />/i//.W. Cl,,m. Leipzig, 1858, Taf vi Fig. 2, .T 

 This work should !><> consulted for the crystalline forms of all physiologically im 

 jiortant substances. See also Ultzmonu u Hoffmann, ./if/a* d. Tam*M%M>fe \Virn. 



- < - f. Hnn-hanl. Innng. Dlts. Rostock, 1889. Al^t in /.'. </. <f. chem. Gesell. 



- 752. 



r a fuller account of the several substance* comprised in this group see 

 ( Jan. /. Chemistry, Vol. i. (1880), p. 425 et seq. 



Cf. HopptSeyfar, Phygiol. Chem. 1877, S 



BopptJMiTbr, '/.i. / /./,./.<;../. <'i,n. IM. u. (is:s). s. 42: ; R<i in. s. .374. 



9 Tolmatflcneff, al-o S. hmi<lt .Mulhcim, li>r. fit. (su!> Choleotprin). 

 7 Al S-hini.lt, It.,-, d ! U IM. MX. (1867 5 !<>. Xunt7., 



./. mnl. ll'-s<. i MOW, Il.td. 1877. S. 625; IHT'.t. S. 



I r.-,|rric.|. Cornet. Rend. T. LXXXIV. 1877, 

 p. 661. Mathiou ot I'rliain. ///'/. ]. I 



<di..now. M,m. d, l'.\m,L /HI/- St. IVtorl. T \ xv i (1879), No. 13. p. 19. 



