218 OF THE BLOOD: 



violet on exposure to oxygen, and losing their transparency on exposure to 

 carbonic acid. Mingled with these are colorless crystals of common salt, 

 acetate of soda, and colorless scales of albumen in combination with acid. 

 The Hccmatoidin crystals observed by Virchow, and stated by him to occur 

 in blood that has long been extravasated, as in old apoplectic clots, and in 

 corpora lutea, appear to be identical with bilirubin, or the coloring matter 

 of bile. The formation of these crystals takes place with considerable 

 rapidity. If a little coagulated pigeon's blood be introduced beneath the 

 skin of that bird, Htematoidin crystals appear in the course of two days. 1 

 The crystals are soluble in ammonia, insoluble in alcohol and acetic acid. 

 Preyer 2 has recently described yet another form of crystal, to which he ap- 

 plies the term of Hrematoin crystals. They are acicular, frequently bent, 

 partly grouped intostellre and doubly refractile. They are insoluble in alco- 

 hol, ether, and water ; but very soluble in weak solution of potash or weak 

 acetic acid. 3 



180. SPECTRUM ANALYSIS OF THE BLOOD. The researches of Brewster, 

 Herschel, and Mu'ller showed that when solutions of various coloring mat- 

 ters are placed in the solar spectrum, certain portions of the light are ab- 

 sorbed, and dark strise or bands appear in the spectrum corresponding to 

 those rays that have been arrested. F. Hoppe 4 found that in a very diluted 

 mixture of blood and water the spectrum exhibited two well-marked dark 

 strite (2, Fig. 116) in the yellow and in the green, both lying between the 

 Fraunhofer lines, D and E. When less dilute, the two lines blend together, 

 and with increasing concentration, the violet and blue, as well as the green 

 and yellow, gradually vanished, till at length only the red remained. Ar- 

 terial and venous blood alike showed the two stride, as did also dried blood, 

 and blood treated with CO. 2 ,CO,H,SH,NH 3 , etc.; but the stride rapidly dis- 

 appeared when acetic or tartaric acid, or caustic alkaline lyes were added 

 to the blood. He further found that the ordiuaiy absorption stride were ren- 

 dered most distinct by precipitating a mixture of blood and water with 

 acetate of lead, and throwing down the lead with carbonate of soda. Prof. 

 Stokes, on repeating the experiments of Hoppe, confirmed them, and at 

 once proceeded to inquire whether it were possible to imitate the change of 

 color of arterial into that of venous blood, on the supposition that it arose 

 from reduction. This he accomplished by adding solution of protosulphate 

 of iron to the blood, with enough tartaric acid to prevent precipitation by 

 alkalies, when the color of the solution immediately became much deeper, 

 and the two absorption bands were at once replaced by a single band (4, 

 Fig. 116) shaded off at the borders, and occupying an intermediate position 

 between them. On exposure to air, the bauds originally present reappeared. 

 Hence he inferred that the coloring matter of the blood, like indigo, is capa- 



1 Langhans, quoted in Fehling's Neties Handworterbuch der Chemio, 1875, B. ii, 

 p. ll'J. 



- Centrnlblatt, 1871, p. 51. 



3 For the best accounts of the crystals of blood see Teichmann, Zcitschrift f. Kat. 

 Mr.l., N. F. iii, 375, viii, 141 ; Ko'lliker, Manual of Human Histology, ISliO; Vir- 

 chow, Cellular Pathology, 18(10, pp. 143-145; v. Gorup-Bcsanez, Phys. Ghem., isiii', 

 pp. 170 11)4; Funkc, Physiologies, 4th edit, 18(>:>, p. 45; Bojanowski, Siebold and 

 Kolliker's Zcitschrift, Bd. xii^ 18(i'2, p. :!1L': Uollett, MoleBchott's Untersuehung., 

 ISC,:!, p. L''_' ; Botteher, Virchow'fl Archiv, 18U5, p. rj<; and p. oT2 ; Zawnrykin, Sitz- 

 iiiisberichte d. k. Akad. zu Wicn, 1805, p. 151; (iwosdew, idem, 18W5; Hoppe- 

 S'\ ler, Mcd -Clicni. Untcrsuch., 1807, p 298 ; Kiihno, I'liysiolosj. Cheinie, 1868, p. 

 188 ct scij ; Tlmdiclmin, Centralblatt, 18(1!), p. 1; Preyer, Die Blulkryslalle, Jena, 

 1871, which lat-t contains all the references up to that date, and gives the fullest 

 ju'connt yet published. 



4 Vire'how's Archiv, lid. xxiii, 18ti2. p. 440. 



6 Proceed. Roy. Soc., vol. xiii, 1863-04, p. 355. 



