18 THE TOXER LECTURES. 



inauguration of this investigation, been in our mind unques- 

 tioned. 



Before entering into details of our own studies, it seems 

 advisable to summarize the o})inions concerning the intimate 

 nature of the healing process in arteries after ligation "nhich 

 are at present supported b}^ the weight of authority, and ai'e 

 consequentlj' accepted by the medical world as beyond dispute. 



Billroth, in his celebrated work on surgical pathology', saj'S 

 that after ligation the plugging of an arterv hy a blood-clot 

 is onl}' a provisional attempt on the part of nature to arrest 

 hemorrhage. The thrombus does not remain in the same con- 

 dition for all future time, but it becomes transformed into 

 cicatricial tissue, shrinks and atrophies, when the arterj'- at the 

 point of division has become solid by the complete fusion of 

 this cicatricial mass with the walls of the vessel. For the 

 completion of this process months, and even 3'ears, are required. 

 In what these changes of the blood-clot actually' consist, the 

 microscope gives valuable evidence. The clot is homogeneous 

 throughout, that is to say, there is no stratification or group- 

 ing of the blood-disks, either of the white or red ; but, on the 

 contrary, they are scattered evenly through the entire coagu- 

 lum. 



It is the further development of the colorless cells of this clot 

 which secures the definite termination of the ivhole pi'ocess. 

 Since the blood-clot, consisting of cells and coagulated fibrin, 

 is at first a non-vascular cellular tissue, which can only at first 

 maintain its existence in thin layers, it is apparent (and obser- 

 vation confirms this) that large blood-clots are not organized 

 at all or only in their peripheral layers, while they disintegrate 

 in the centre. 



Wliat are tliose cells which organize the thrombus? and 

 whence do they come? 



On a i)revious page of this distinguished author's most ex- 

 cellent work a sentence appears wliich places Billroth upon 



