The products of this secondary action are known as " purulent deposits," or " lobular abscesses." Strictly speaking, they are not deposits pus ; but the pus is "translated" from one part to another, and there becomes the originator and centre of a fresh abscess.
The actual mode of production of these lo bular abscesses has been the subject of much discussion ; but the evidence upon the va rious points appears to resolve itself into the following explanation. The pus-cells being bodily introduced into a vein, or generated in it, pass forward in the circulation till arrested in the capillaries by their size being too great to admit of their passage : they then excite inflammation of the parenchyma of the affected organ, which leads to condensation, and, sub sequently, to suppuration : the pus-cells being the excitants of the inflammation, which is suppurative, not only from its intensity, but from the fact that pus germs are furnished by the same body as originates the inflammation, and thus more pus is generated.
The appearances of these local abscesses, which are, strictly speaking, foreign to our present subject, are determined by the cha racter of the organ in which they occur.
There appears to be some general laws as it respects the development of these abscesses. They occur in those organs which are most vascular, and through which the largest quan tity of blood passes in the smallest space of time; thus the lungs and liver are affected the most abundantly. Again, after the blood has been infected and the pus added to it, that system of capillaries is first affected, through which the fluid first passes ; the capillaries, as it were, filtering off the pus-cells and retaining them. Thus, if pus gets into the systemic veins, the capillaries of the lungs will be the first to arrest their progress ; and when this happens, as is generally the case, lobular ab scesses are most abundantly, or exclusively, found in those organs, and when found else where also are most advanced in the lungs : when, however, the portal system is the vehicle of the pus, as occasionally happens after oper ations on the rectum, for example, we find the abscesses in the liver. These laws are quite correct in the main ; but there are some ex ceptions to them, and these exceptions are quite explicable ; for though pus-cells are for the most part too large to pass capillaries, especially with their tendency to coagulate blood, they may nevertheless pass through some of the larger ones ; and it must be ad mitted that disintegrated pus globules may pass through the smallest vessels : hence, in some instances, the laws here suggested are not exemplified.
The results of phlebitis are either suppura tion, resolution, or obstruction, the consequence of organisation of the effused lymph. Upon the latter subject some observations are ne cessary.
Obliteration of of veins, the result of phlebitis, may be either incom plete or complete. Hasse mentions two forms of partial obliteration of veins ; the first of which has also been described by Carswell. This form consists of a thickened and turgid condition of the vessel's walls, as if they had been macerated ; at the same time they are closely connected with the surrounding areo lar tissue. Within the vein, and intimately connected with the lining membrane, is a hol low cylinder of fibrin, firm and whitish on its exterior, and soft and dark-coloured within ; the interior being bathed with the circulating blood. Dr. Carswell's explanation of this, in which Hasse coincides, is that the soft centre of the plug is carried away before the circu lating current, whilst the exterior becomes organised and united with the interior of the vein.
In the other form he describes the vein as reduced to a whitish cord, and filled with an organised plug. " Betwixt this plug and the thickened coats of the vessel, round about the periphery of the former, were several little canals, which, running along the whole extent of the vein, had already begun to re-establish the circulation. In all probability the impulse of the blood below had, during the first period of inflammation, here and there severed the plastic plug from the parietes of the vessel ; subsequently, the above plug being organised, and the intervening blood absorbed, several peripheral channels would form, instead of a single central one." * In complete obliteration the vein diminishes in size, shrinks nearly to a cord, and becomes pale and soft. The plug also becomes reduced in size and organised, and adheres firmly to the lining of the vein. How the plug re ceives its vessels and communicates with the vasa vasorum of the vein, I am not prepared to state. But fibrin thus isolated probably has the inherent power of generating vessels, which ultimately communicate with those of neighbouring textures. The secondary con sequences of obliteration of veins, — cedema, Phlegmasia dolens, &c. cannot here be con sidered.