282 THE BLOOD. 



have been washed out, it is necessary to add a small crystal of the 

 salt to the acid before boiling. 



Hemochromoyen. This is also called reduced hematin, and re- 

 sults when hemoglobin is decomposed by alkalies, or acids, in the 

 absence of all oxygen. Its crystallizability has not been demon- 

 strated. Gamgee questions whether hemochromogen exists pre- 

 formed in hemoglobin and its compounds. 



Hematoporphyrin. If to hematin strong sulphuric acid is 

 added, the iron is dissolved out, making ferrous sulphate, and 

 hematoporphyrin or iron-free hematin re- 

 mains. It is regarded by some as iso- 

 meric with bilirubin. The formula as 

 given by Hoppe-Seyler is C 34 H 3 gN 4 O 6 . It 

 has in acidulated alcoholic solutions a pur- 

 ple color, assuming a bluish-violet tint when 

 made strongly acid; but alkaline solutions 



\are red. Solutions of this substance " ex- 

 ^g^gg-J 8 * 8 *' hibit a magnificent fluorescence " (Gamgee). 



It is found in small amount in normal urine, 

 FIG. 151. Hemiu, or and in large quantity in chronic poisoning 



Teichmann's crystals, from f rom t ] ie uge Q f gulphonal. 



blood-stains on a cloth TT . . -,. TIT iij i 



(Huber). Hematoiain. In blood-clots, such a^ 



form in apoplexy, where a blood-vessel 



of the brain ruptures, a crystalline substance is found, to which 

 Virchow gave the n|ime hematoidin. It is beyond question a deriv- 

 ative of hemoglobin. Its formula is given as C 16 H 18 N 2 O 3 , and it 

 is identical with bilirubin. 



Histohematins. In the muscles and other tissues of the body 

 coloring-matters are found which are called histohematins, which 

 may be related to hemoglobin, but the relationship has not as yet 

 been established. 



Spectra of Hemoglobin and its Derivatives. Before discussing 

 the spectra of hemoglobin and its derivatives, it will not be inap- 

 propriate to describe the spectroscope and its application to the 

 differentiation of the coloring-matters of the blood in the varied 

 forms in which we have found them to occur. For a more de- 

 tailed description of spectrum analysis our readers are referred to 

 the many excellent treatises on physics. The wonderful adapta-* 

 bility of spectrum analysis to the solution of many physiologic 

 problems may be illustrated by the statement that by its means 

 31700000 f a milligram of sodium can be detected, and a corre- 

 sponding delicacy of analysis is true of other substances ; thus the 

 rapid absorption and diffusion of certain substances have been de- 

 termined by the spectroscope. Roscoe, in his Spectrum Analysis, 

 states that twenty-four minutes after injecting 3 grains of lithium 

 salt under the skin of a guinea-pig the lithium is found to be 

 present in the crystalline lens and every part of the body, it only 



