1014 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



of ethereal sulphate in the urine gives an indication of the amount of intes- 

 tinal putrefaction. It does not disappear in starvation, mucin and nucleo- 

 proteid of bile and intestinal juice furnishing material. 1 If the intestinal 

 tract be treated so as to make it antiseptic, the ethereal sulphates disappear 

 from the urine. 2 Diarrhoea likewise decreases their amount, obviously from 

 the short time given for putrefaction. 



Inosit. This is the hexatomic phenol of hexahydrobenzol, C 6 H 6 (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^HngoN-^FeSaC^s (Zinoffsky's formula for haemoglobin in horse's 

 blood). Haemoglobin is found in the red blood-corpuscle. United with oxygen it forms 

 oxyhaemoglobin, 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 

 oxyhaemoglobin crystals are numerous, but all depend on getting the haemoglobin into solu- 

 tion. If the corpuscles in cruor be washed with physiological salt-solution, then treated 

 with distilled water, the HbO will be dissolved ; on shaking with a little ether the stroma 

 will likewise dissolve ; after decantation and evaporation of the ether, at the room's tem- 

 perature, 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 lie collected, 

 redissolved in water, and reprecipitated 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 convert oxyhaemoglobin 

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

 globin is without doubt formed in the body from simple proteids by a synthetic process, 

 (For further information see pp. 973 and 1015, and likewise under the section on Blood.) 



CO-Haemoglobm (see p. 960). 



NO-Haemoglobin (see p. 956). 



Methaemoglobin. This has tbe same composition as oxyhaemoglobin. It is found 

 in blood-stains, and may be considered as oxyhaemoglobin which has undergone a chemical 

 change whereby its oxygen is more firmly bound in the molecule. 



Haematin, C 32 H 32 N 4 4 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 

 acidified 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 

 warmed, characteristic brown microscopic crystals ofhcemin, C 32 H 30 N 4 Fe0 3 . HC1, crystallize 

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

 tive of the presence of blood. 



Haemochromogen, C3 4 H 36 N 4 Fe0 5 . If reduced haemoglobin be heated in sealed tubes 

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



1 Von Noorden : Pathologic des Stoffwechsek, 1893, p. 163. a Baumann, Op. cit., p. 129. 



