REPARATOKY INFLAMMATION IN ARTERIES. 43 



pressure had been applied, had met and formed an extensive 

 union. They consisted almost entirely of spindle and stel- 

 late cells with long and anastomosing processes. They were 

 observed to be permeated by a capillary and canalicular 

 vascular network. At this early date the vessels from this 

 plastic formation had extended as far as the inner layers of the 

 media to a depth corresponding to the extent of the cellular 

 infiltration above alluded to, but had not gone further outward. 

 There was not the least trace of an anastomosis having yet 

 been established with the vasa vasorum. The vasa vasorum of 

 the adjacent adveutitia did not yet exhibit any tendency to 

 send vascular loops into tlie media. The blood coagula above 

 and below this point of activity showed the usual serpentine 

 lamellation, and presented no appearance of progressive or- 

 ganization. At the point of ligature the vessel-walls and the 

 connective tissue were in a state of purulent infiltration, the 

 ligature having nearly ulcerated through. 



Fig. 9. Thrombus ten days old. A typical view, in longi- 

 tudinal section, of the condition invariably found to be present 

 after ligation in this manner. Low power. 



A. Position of ligature. B. Level of application of forceps. 

 a. Adventitia. m. Media, c. Cellular tissue, p. Cellular for- 

 mation at the bottom of clot, non-organized and apparently 

 not larger than such an accumulation usually is at five days ; 

 it consists mainly of cells similar to white blood-corpuscles ; 

 onlj^ a few epithelioid cells are scattered through it, and applied 

 along the elastic layer of the tunica intima ; no granulations 

 springing from it penetrate the crevices of the laminated clot 

 (o?) immediately above. 



The blood-clot (d) is seen to be formed of two separate por- 

 tions of coagulum, exhibiting the previously named serpentine 

 lamellation. This blood-clot is firmly adherent at the bottom, 

 but possesses only slight bands of union with the lateral walls 

 of the vessel. L. Lumen of the vessel. While manipulating this 



