REPARATORY INFLAMMATION IN ARTERIES. 55 



of ligation and the first collateral branch above. See Figs. 1 , 

 5, and 6. 



7th. The rapidity of the healing process is usually propor- 

 tionate to the growth of the plastic clot. 



8th. The growth of the plastic clot is at first somewhat stimu- 

 lated by the presence of a fibrinous or blood clot. The pres- 

 ence of the latter is not essential, for the formation and organi- 

 zation of the plastic clot occasionally take place without it. 



9th. The plastic clot begins to present signs of commencing 

 vascularization as early as the sixth day. 



10th. The organizable or plastic clot is vascularized at first 

 indejjendently of the vasa vasorum. Some days before any 

 trace of a vascular communication between the plastic clot and 

 the vasa vasorum can be discovered, the former is thoroughly 

 permeated by a rich capillary network which is in communica- 

 tion with the open lumen above the thrombus, by means of 

 blood channels or sinuses of considerable size located mostly 

 in the superior portion of the plastic clot. The first vascular 

 formation generally appears in the peripheral portions of this 

 clot 



11th. Usually between the fiHteenth and the thirtieth day after 

 ligation an anastomosis is established between the vessels of 

 the clot and those of the walls of the artery. The communica- 

 tion is established at the bottom of the arterial stump where 

 the intima and media have been cut through by the ligature. 

 At this date the elastic layer of the intima, from the top nearly 

 to the bottom of the clot, is sharply defined, presents little evi- 

 dence of softening, and offers no perforation for the establish- 

 ment of a lateral anastomosis between the vasa vasorum and 

 the vessels of the clot directly through the sides of the artery-. 

 See Fig. t. 



12th. The plastic clot, b}' a gradual metamorphosis into cica- 

 tricial tissue, and by a subsequent cavernous transformation of 

 the latter, finally disappears — the only remains of the vessel 

 and of the clot being a tough fibrous cord. 



