Further Evidence Of The Phlebitic Process, both in reference to its own nature and that of its products, and to its highly important character, is afforded by numerous secondary conditions, which we shall briefly notice in the following remarks, referring our readers to our previous observations on the subject in Diseases of the Blood.

a. The immediate consequence of the phlebitic process is a diseased condition of the blood, arising from the absorption of the morbid products, which constitutes the basis of all the subsequent secondary phenomena. This disease generally induces degeneration of the blood, according to the character of the product, either into a so-called phlogistic condition (haemitis, hyperinosis), or into pyaemia. Hence arise: b. The processes of stasis and coagulation of the blood in various portions of the capillar]/ system (lobular processes, deposits, metastases, capillary phlebitis), with the different metamorphoses of such a coagulation; namely, shrivelling to a fibroid callus with atrophy of the tissue, or purulent, ichorous fusion with similar destruction, necrosis of the tissue; processes of coagulation in larger vessels, more especially the veins; and finally in the heart itself under the form of different vegetations.

c. The allied processes of stasis and of exudation into the parenchymatous structures, as well as upon the membranous, serous, and mucous surfaces, with the fusion of the substratum, which is especially perceptible on the mucous membranes, and with suppuration and necrosis of the tissue.

This general infection of the blood by the product of phlebitis, together with the further phenomena depending upon that process, does not, however, invariably take place, - a circumstance that some observers attempt to explain, in imitation of Cruveilhier, by the so-called sequestration of the vein. Thus, for instance, the coagulation of the blood on the limits of the inflammation, and the exudation into the vein, are supposed to isolate the inflammatory product - the pus - and prevent its absorption into the blood.

We have been led, by extensive experience, to adopt the following views in reference to the solution of these two intimately associated questions regarding the cause of the non-occurrence of a general infection, and the significance of the so-called sequestration, as a special means of arresting the process.

The non-occurrence of a general infection of the blood in phlebitis would appear to be frequent, if we judge from observations on the living subject; but, on the other hand, it is rarely noticed after death, where the phlebitis which is brought under our observation is generally characterized by purulent exudation.

In the latter cases, therefore, the exudation must be absorbed into the blood, and carried away with it from the seat of its formation.

The reason of the non-occurrence of a general infection depends, in our opinion, upon the fact of the blood coagulating at the place of the exudation, and upon the rapidity with which the whole of the blood, or one of its strata, is coagulated in consequence of the absorption of the inflammatory product; whence the course of the recently deposited or still exuding product is at once arrested.

As, however, this coagulation in the ordinary and more frequent cases is not effected immediately, but requires (as we see exemplified in the frequent development of coagula in a section of the vascular system remote from the infected portion of the blood) that the heterogeneous substance must remain for some time in contact with the blood, we are able to explain why a portion of the exudation is in general carried onwards by the circulation, and the blood is then infected before the coagulation can be established in the vessel.

A sequestrating fibrinous plug must be distinguished from the coagulum originally filling the vessel, and induced in the blood-current by the absorption of the exudation.

It is certainly true, that in every case of phlebitis the coagulation of the blood extends beyond the limits of the inflammatory centre, along the vessel, and the coagulum filling it. In order to comprehend the significance of this coagulation as a means of sequestration, it will be necessary for us to form a clear idea of the conditions requisite for its formation.