Phlebolites have been made the subject of chemical analysis. According to Gmelin, the following is their composition : — This analysis has been repeated with the same general results by Prout, Kemp, Hasse, and Lehmann. They have since been sub mitted to another analysis by Schlossberger, who has given his results more in detail, as follows : — Phosphate of lime - - 50.1 Phosphate of magnesia - 13.7 Carbonate of lime - - 8.3 Organic matter - 20•1 Water - - - - 6* I Loss - - - - 1'1 100• These, then, are phlebolites completely ma tured. In those less completely developed the phlebolite consists of an altered coagulum, in the centre of which is earthy matter, sur rounded by white fibrinous concentric layers. Cloquet has described one, which was not fully formed, in which the calcification was incomplete. It was taken from the inferior cava, and consisted of a fibrinous mass, con taining a calcareous centre, from which a number of rays of the same substance passed through the fibrinous matter toward the cir cumference. Cloquet describes one of similar structure, which he saw in Scemmering's mu seum, and which was also taken from the inferior cava. In a still more primitive condition these calculi are recognisable. " On drying the coagula found within dilated veins, previously to their having coalesced with the internal membrane, they shrink together, grate under the knife, and exhibit calcareous induration at certain points, even in cases where it had not been at all suspected."* As regards the origin and development of phlebolites, only one opinion is now enter tained, namely, that they are developed from modified coagula. Andral, however, gives the following explanation. After speaking of cal careous degeneration of the coats of veins, be goes on to say, " these calcareous concretion•, instead of lying between the coats of the veins, sometimes push the internal membrane before them, and project into the interior of the vessel ; the membrane in such cases ge nerally contracts behind the concretion, and forms a peduncle, which serves to attach it to the side of the vein. It is probable that these peduncles are sometimes ruptured or ab sorbed, and thus the concretion is completely detached from its connection, and drops loose into the vessel. This rationale may serve to explain the origin of some of those calcareous concretions which have been found in the centre of the venous coagula.t Hodgson imagined that phlebolites were formed in the neighbouring textures, and found their way into the veins by progressive absorption.
Dr. Carswell has described and illustrated the true method of their formation in detail, exhibiting their successive changes in the pro gress of maturation. At first a coagulum of blood is formed, which becomes condensed and laminated in the centre ; the colouring oatter of the blood subsequently becomes ab sorbed, and leaves ordinary yellow fibrin ; this also becomes lamellated throughout. After this calcification commences in the centre and proceeds outwards till the whole is calcareous.
This mode of formation is maintained also by Otto, Ticclemann, Lobstein, Crtiveilhier. Errhman, Briquet, and Hasse.
The position of the phlebolite within the vein, and the condition of the vein and phle bolite respectively, are subject to much variety.
In the dilated pouches, which sometimes form in the sides of the veins, coagula arc fre quently produced, which may terminate in phlebolites. The pouch being filled, the walls
become atrophied, the inner surface becomes rough and cellular, and closes firmly round the calculus, sometimes making it appear ex ternal to the vein. At other times, not only the pouch, but the entire calibre of the vein, becomes implicated and stuffbd with calcifying coagulum ; in this case a portion of the tube becomes obliterated. In other instances the phlebolite is free in the cavity of the vein, is loose and movable, and the vessel that con tains it is still permeable to the circulating current. Such phlebolites, though loose and movable, are frequently surrounded by coagula of blood ; sometimes by a layer of fibrin. They have occasionally been surrounded by a thin layer of fibrin, and attached at one point to the side of the vein bra sort of peduncle, the rest of the body hanging free into the cavity of the vessel. Tiedemann very naturally suggests that in these cases the peduncle is produced by the effusion of coagulable lymph, the result of inflammation, caused by the presence of a foreign body.
Phlebolites have been discovered in very many of the veins : they have been found in the vena cava inferior, the renal, the dorsal, the common iliac, anterior and posterior tibial, the saphena and other superficial veins of the lower extremities, the hypogastric veins ; also in the uterine, the vaginal, spermatic, vesical, prostatic, and hwmorrhoidal, veins. They have likewise been seen in the splenic and mesen teric veins. Their most frequent and most abundant position is in the veins of the pelvic viscera. In number they vary considerably : there are generally, though not always, more than one. Tiedernann found thirty-six in the spermatic veins of one individual,—fifteen in one, and twenty-one in the other.
They occur almost always after middle age. They produce no injury or inconvenience ; nor is their presence known, except in a few situations, during the life of the individual.
There are some general circumstances re lative to phlebolites which are striking and curious. They always occur in veins below the diaphragm,— in depending vems,— in veins which circulate their blood against the force of gravity.
According to Hasse, they always occur in conjunction with phlebectesis.
They frequently, perhaps generally, occur in veins returning the blood from diseased organs, —from a diseased testicle or prostate, from an ulcerated rectum, from an inflamed or cancerous uterus, from an ulcerated leg, &c. Examples of all these are on record.
What, then, determines their development ? This question it is not easy to answer ; all we can say is, that those circumstances which fa cilitate mechanically the coagulation of the blood, favour their production ; and it is not improbable also that a vitiated state of blood may predispose to and favour their develop ment : it is certainly probable that the pre disposing causes, whatever they are, may be started into activity and be made efficient liar the production of these bodies, by some temporary local disturbance of the circulation, or by some slight subinflaminatory condition, which varicose veins readily take on, and which, were it not for the existence of pre disposing circumstances, would soon be re solved.