48 THE TONER LECTUUES. 



By this time (certainly not more than twentj' seconds after the 

 first interruption of the arterial current), the anastomosing 

 capillaries which had established the collateral circuit were 

 nearly as wide as the artery itself, and were beating quite as 

 violently. The arterial flow beyond this point did not now 

 seem to be at all affected. The establishment of the collateral 

 circulation in the frog's tongue, after the experiment related 

 some distance above, did not take place so rapidly, since at 

 least fifty seconds were necessary for its free establishment. 



"What is the origin of the cells which constitute the organ- 

 izable plastic clot ? 



After the study of our preparations we have no doubt that 

 the great masses of them are derived immediately from the 

 endothelial and other cell elements of the tunica intima, by a 

 process of proliferation excited partly by the irritation caused 

 by the ligature, the needle, or- forceps, and stimulated b}' the 

 unwonted supply of nutrient material constantly retained with- 

 in their reach, in consequence of the sluggish movements of 

 the fluids of the blood. 



Whence come those colorless elements which have been 

 brought from some distance by the blood current — those both 

 of the plastic and of the fibrinous clots of a thrombus such 

 as we have been considering? 



Let us consider first the migrated leucocytes, whose presence 

 in the plastic clot in considerable numbers I have previously 

 mentioned, and t© whose agency Billroth and llindfleisch as- 

 cribe, in a great degree, that organization of the fibrinous clot 

 which they believe in. 



Do they come directly through the walls of the vessel, or 

 do they come principally, by way of the arterial current, from 

 above the thrombus ? Bubnoff declares that many of the 

 white blood-corpuscles found in a blood coagulnm after liga- 

 ture of a vein, have travelled directly through the vessel-wall. 

 Billroth rei)eated the experiments of Bubnofl, and extended 



