OF PROTEIN-BASIS.
Blood effused into the tissues may be either (a) absorbed wholly or partially, or (b) not absorbed.
(a) 1. If the blood be absorbed wholly, no vestige of the hmmorrhage may ultimately be traceable, even in the condition of the tissue amid which it occurred ; or (as is more com mon) even after the total removal of the blood elements, sorne slight puckering, changed den sity, or changed position of the proper texture of the organ (of the brain, for instance) re veals the fact that hmmorrhage has occurred. ln either case, blood has escaped from the vessels without leaving even the potential ele ments of a growth behind it. 2. Partial ab sorption acts commonly upon the watery and colouring matters of the blood, the fibrin alone remaining : this fibrin (fibrinous hmmatoma, from cat,a,ro.y.m, blood-tumour), may form a single mass, as is usual in the parenchymata, or several fragmentary parcels, as happens generally in the serous cavities. Partial ab sorption, in a class of rarer cases, acts first upon the fibrin ; the effused blood becomes more thin and aqueous,and sometimes (spread ing by infiltration and endosmosis amid the surrounding textures) is thence eventually absorbed : here no residue, referrible to the present head, remains behind.
(b) When not absorbed, blood either (1) ex cites inflammation and its consequences ; or (2) remains stationary in a fluid condition; or (3) assumes the characters of dark grumous semi coagula ; or (4) undergoing inspissation from deprivation of its watery parts, a firm co agulum, growing daily more solid, remains be hind : in this last instance we have a coloured hmmatoma.
A haematorna is then a fibrinous mass, coloured or not, arising from hminorrhage.
Before us (Univ. Coll. Mus.) lies a colour less hmmatoma of the spinal meninges in the cervical region, the result of a blow. Its size is that of a walnut ; it is of pale straw-colour, homogeneous on superficial view, but finely granular when closely inspected. Hmmatoma may, however, be coarsely loculated ; the walls of the loculi being solid, the contents more or less fluid, or gelatiniform-looking. Such tumours (while unchanged in characters) exhibit microscopically the qualities of fibrin, — fibrils gelatinizing with acetic acid,—anior phous fragments, granules, and molecules. Their colour varies ; it may be of deep yellow, somewhat buff; tint,— and commonly is so, in the spleen and kidney, for instance. Their chemical reactions are those of fibrin.
The surface of a hmmatoma is smooth ; a coating of epithelial structure, rapidly form ing, gives it this character. A hwmatoma is rarely encysted; for though nothing is more common than the formation of a cyst round effused blood (apoplectic cyst) as a general fact, y-et this process is rarely wit nessed, where the progress of absorption has been of the kind to produce a hwmatorna.
Hzematomata may probably form wherever blood, thrown out from the vessels, is re tained. Thus (1) they are seen in the serous cavities,—as the peritonacum and pleura, where they have more than once been found in the stages of transition ; and in synovial cavities, where, as John Hunter long since maintained, they frequently form the so-called " loose car tilages " of joints. (2) Amid membranous structures,—as for instance, under the choroid coat, vvhere they have been frequently mis taken for carcinoma ; into the great cavity of the arachnoid (Univ. Coll. Mus.)—a not un common seat ; between the arachnoid and dura mater of the skull, where, we feel posi tive, they have occasionally been the origin of minute fibrous tumours ; under the mucous lining of the uterus, where a similar destiny sometimes awaits them; under the periosteum, either when the blood has flown through the influence of external injury, or through the influence of causes, partly traumatic, partly spontaneous, as in that singular affection of new-born infants —cephalhzematoma. — (3)
In parenchymatous organs, as the brain, the spleen, the kidneys, the lung (in all of which we have repeatedly seen them), an'd more rarely in the mamma, where they have often, clin ically, played the part of cancers.—(4) In the cellulo-muscular structures of the limbs, as the result of contusions or spontaneous hmmorrhage.—(5) In the proper substance of certain new products, especially encephaloid cancers.—(6) In cavities accidentally formed in the tissues, as in tuberculous cavities in the lung. (Univ. Coll. Mus.) Various changes of deep interest may occur within the substance of a hmmatoma. Unsup plied with vessels, as it commonly is, it cannot be the seat of interstitial hemorrhage ; but blood may nevertheless infiltrate its substance derived from the ruptured vessels of surround ing textures,— just as extra-vascular tissues may become infiltrated with exudation-matter produced by inflammation, not in them, but be side them.* Saline precipitation is a common occurrence; such is often the origin of ossifortn particles or masses in the brain ; of similar masses in advanced cephalhmmatoma t ; and such (as elsewhere shown by us) is almost in variably the source of free calcareous and ossi form products in cancer : the changes con cerned in the production of a phlebolith are one by one gone through. That melanic pigment niay form in heematomata appears extremely probable, from certain observations which we made several years ago on some specimens of melanic tumour ; full reference to these will be found in the section on Melanoma. We have in a previous section spoken of the doubt still hanging over the question of the possible evo lution of simple effused blood into Forma tions of' definite structural characters. The question appears to be all but absolutely decided in the affirmative by a tumour now before us (Univ. Coll. Mus.), in the substance of which the transition from the characters of hmmatoma to those of fibrous tumour, is per fectly traceable in point of colour, consistence, and textural arrangement. Bone-formation may take place from blood effused in localities where a tendency to such formation naturally exists, and where formative life is active. Thus, in the instance of sub-pericranial ce phalhxmatoma, the smooth gelatinous-looking membrane, which invests the blood, may be.. come so perfectly ossified, that it has, in this state, been evidently mistaken by some ob servers for the outer table of the bone, and a figment, in the shape of interstitial or diploic cephalhmtnatoma, invented to meet the dif ficulty. Even in the centre of the fibrinous residue of this effused blood actual bone has sometimes been seen.
Concerning the vascularization of blood in substance we have already given our opinion. Hwmatomata in the brain have been found dis tinctly vascularized in cases where there was no evidence that plastic lymph had been added to the extravasated blood ; and M. Louis' description, already- referred to, of a vascu larized coagulum in a tuberculous excavation of the lung is peculiarly satisfactory.
Blood retained in its proper canals may coagulate and undergo various changes. In the arteries, cellulo-fibrous evolution and cal cification occur in stagnating blood without the intervention of an inflammatory process : in the veins we have seen vascularized coagula injected ; and the formation of phleboliths and arteroliths illustrates saline precipitation. Vascularized coagula in the heart have been described by Rigacci, Burns, Bouillaud, and others.