24 THE TONER LECTURES. 



First Series. — Microscopic examination of sections from 

 the first series demonstrated the fact that the apparent sequen- 

 tial order of the various phenomena exhibited throughout the 

 series, presented a marked uniformity. 



Nearly every preparation tvvent3-four hours old showed, 

 under a low power and in longitudinal sections, a blood-clot, 

 not unusually extending as far as the first collateral branch. 

 This clot was usually egg-shape, and it did not fill the entire 

 calibre of the vessel. Ordinarily it was adherent to the 

 vessel-wall only at one side, while it was slightly separated 

 from the opposite side. It did not extend quite down to the 

 point of ligature, for the bottom of the little cup formed by the 

 constricting action of the thread upon the arterial walls was 

 generally covered over several layers deep with colorless cells, 

 and it was upon this cushion of colorless cells that the butt-end 

 of the blood-clot rested. The outer surface of this cup-shape 

 cushion of colorless cells was everywhere closely adherent to 

 the inner membrane of the vessel-walls. At the sides this cup- 

 shape cushion extended along the inner surface of the vessel- 

 wall for a considerable distance from the ligature — occasionally 

 up as far or even farther than the apex of the blood-clot. The 

 bottom of the blood-clot was adherent to the bottom of this 

 cup-shape cushion of colorless cells, and it was also adherent 

 to one of its sides. To avoid confusion, I shall hereafter refer 

 to the blood coagulum as the blood or fibrinous dot, and in 

 distinction shall speak of the cup-shape cushion of colorless 

 cells as the cellular or plastic clot. The number of the color- 

 less cells of the plastic cup or clot, or, in other words, the thick- 

 ness of its walls, rapidly deci'eased in proportion to the remote- 

 ness from the point of ligation. Concerning the constitution of 

 the fibrinous or blood clot, the declaration is emphatically made 

 that, when viewed in longitudinal section, in not one solitary 

 instance in any of these series was it observed to be homoge- 

 neous in structure ; but that, on the contrary, when so viewed 



