THE CHEMISTRY OF THE ANIMAL BODY. 573 



indol and phenol, holding them until the requisite synthesis between them 

 and .sulphuric acid occurs, and thereby rendering them non-poisonous. 1 



Inosit. — This is the hexatomic phenol of hexahvdrobenzol, C 6 H c (OH) 6 . 

 It was long mistaken for a carbohydrate. It has been found in muscle, liver, 

 spleen, suprarenals, lungs, brain, and testicles ; likewise in plants, in unripe 

 peas and beans. After drinking much water it may be washed out in the 

 urine, and perhaps for this reason is often found in the voluminous urine of 

 the diabetic. When fed it is burned ; also by the diabetic. Its origin is 

 unknown. 



Substances of Unknown Composition. 



Coloring Matters in the Body. 



Haemoglobin, C 712 H U30 N 2U FeS 2 O 24 5 (Zinoffsky's formula for haemoglobin in horse's 

 blood). — Haemoglobin is found in the red blood-corpuscle, probably in chemical union 

 with the stroma. 2 United with oxygen it forms oxyhaenioglobin, which gives the scarlet 

 color to arterial blood ; haemoglobin itself is darker, more bluish, and therefore venous 

 blood is of a less brilliant red. Methods for preparing oxyhemoglobin crystals are 

 numerous, but all depend on getting the haemoglobin into solution. If the corpuscles 

 in cruor be washed witli physiological salt-solution, and then treated with distilled water, 

 the HbO will be dissolved; on shaking with a little ether the stroma will likewise dis- 

 solve; after decantation and evaporation of the ether, at the room's temperature, the 

 solution is cooled to — 10° and a one-fourth volume of alcohol at the same temperature 

 added; after a few days rhombic crystals of oxyhaemoglobin may be collected, redis- 

 solved in water, and re precipitated for purification. The crystals may be dried in vacuo 

 over sulphuric acid. Once dry they may be heated to 100° without decomposition, but 

 in aqueous solution they are decomposed at 70° into a globulin and haematin. the latter 

 having a brown color. This difference in color gives the distinction between "rare " and 

 "well-done" roast-beef. Gastric and pancreatic digestion likewise converts oxyhaemo- 

 globin into a globulin, which may be absorbed, and haematin, which passes into the feces. 

 Haemoglobin is without doubt formed in the body from simple proteids by a synthetic 

 process, (for further information see pp. 529 and 574, and likewise under the sen ion 

 on Blood.) 



CO-Haemoglobin (see p. 51 7). 



NO-Hsemoglobin (see p. 512). 



Methsemoglobin.— This is found in blood-stains, and may be considered as oxyhaemo- 

 globin which has undergone a chemical change whereby some of the loosely combined 

 oxygen has been liberated. 3 



Haematin, C 32 H ;!2 N 4 0.,Fe. — This is a cleavage-product of haemoglobin in the presence 

 of oxygen. (See above, under Haemoglobin). It is not itself a constituent of the body. 

 It is insoluble in dilute acids, alcohol, ether, or chloroform, but is soluble in alkalies or in 

 aeiditied alcohol or ether, showing characteristic absorption-bands. If a little dry blood 

 be placed on a microscope slide with NaCl and moistened with glacial acetic acid, and 

 wanned, characteristic brown microscopic crystals of licemin, I ' 1 1 N , Fe( I 1 1 1 '1. crystallize 

 out. If these crystals and the spectroscopic test be obtained, one can be absolutely posi- 

 ti\ c of the presence of Mood. 



Haemochromogen, (VJT^NgFe.^. — This substance has the same composition as 

 haematin, only it contains less oxygen. 4 If reduced haemoglobin be heated in scaled tubes 

 with dilute acids or alkali in absence of oxygen, a purple-red compound is produced called 

 1 Herter and Wakeman : Journal of Experimental Medicine, 1899, vol. iv. p. 307. 

 3 Read .Stewart, G. N.: Journal of Physiology, 1899, vol. xxiv. p. 238. 



3 Zeynek: Archivfur Physiologic, 1899. S. 460. 



4 Zeynek: Zeilschrift fiir physiologische Chemie, 1898, Bd. 25, S. 492. 



