304 COLOURING MATTERS. 



dissolve in alcohol containing sulphuric acid or ammonia, and be 

 again precipitated by neutralisation of the fluid ; this is, however, 

 not invariably the case. Virchow has very carefully examined the 

 behaviour of this body with concentrated alkalies and mineral acids ; 

 these agents, however, do not act in precisely the same manner on 

 all specimens of this pigment ; on the addition of hydrate of potash, 

 a fiery red tint is developed, the mass becomes gradually loosened 

 in its texture, and becomes disintegrated into red granules which at 

 length dissolve ; on neutralising the alkali the substance is, how- 

 ever, not again precipitated. When a concentrated mineral acid, 

 sulphuric acid, for example, acts on it, it causes the sharp outlines 

 of the crystals to disappear ; and the colour of the roundish frag- 

 ments, after first becoming brownish-red, passes through successive 

 shades of green, blue, and rose-tint, till it finally terminates in a 

 dirty yellow. Iron may sometimes, but not always, be detected 

 in the acid fluid containing the decomposed heematoidin. 



Hsematoidin may always be found in the sanguineous extrava- 

 sations occurring in consequence of the bursting of the Graafian 

 vesicles at the periods of menstruation or conception, and frequently 

 occurs in old extravasations in the brain, in obliterated veins, 

 hsemorrhagic infarctus of the spleen, in subcutaneous sugillations, 

 and in purulent abscess of the extremities. (Virchow.) It appears 

 from Virchow's observations that these crystals may form from 

 seventeen to twenty days after the occurrence of the extravasation. 

 Kolliker* has observed the formation of crystals of this nature 

 within the corpuscles in the blood of certain fishes ; these crystals 

 were however, soluble in acetic acid, potash, and nitric acid. 



Although every care and precaution have been taken, both 

 Virchow and I have failed in obtaining these crystals of modi- 

 fied hsematin either from solutions of blood or of heematin 

 itself; but yet those who still assign an important part in the 

 animal body to vital forces, must grant that under the necessary 

 conditions, haematoidin may be produced out of the body from 

 haematin, since this kind of metamorphosis occurring in extravasa- 

 tions in all respects exhibits the character of a disintegration, that 

 is to say, of a purely physical and chemical process. Moreover, 

 Kolliker's observation gives us room to hope that we may be able 

 to obtain crystallisable hsematin or hsematoidin from the blood of 

 the lower animals, fishes, for example, so as to submit it to an 

 accurate chemical examination. 



* Zeitschr. f. wiss. Zoologie. Bd. I, S. 266. 



