20 THE TONER LECTURES. 



flatten tliemselves upon the elastic laj'ers parallel with the sur- 

 face of the latter, still through the whole of the accumulation 

 cells cau be seen occupying every conceivable position, and, 

 consequently, presenting widely varying profiles. In conse- 

 quence of being viewed in profile, many of the cells appear to 

 be spindle-shape. Interspersed among these epithelioid cells are 

 to be found also many round granular cells, precisely similar 

 in size and general features to the white blood-corpuscles. In 

 still greater number are to be seen round or polygonal granular 

 cells twice and even three times the size of the latter. Besides 

 these three general types of cell elements, a- few red blood- 

 corpuscles can be distinguished here and there. Examining 

 this cellular accumulation tliroughout its whole extent, it was 

 observed that, in i)roportion as the distance from the ligature 

 increased, the endothelial cells along the sides of the vessel 

 indicated a smaller degree of activity or irritation. The tunica 

 media nowhere, except at and immediately above the situation 

 of the thread, showed decided signs of increased activit3^ It 

 might be judicious to remark, however, that in the portion of 

 the media immediately beneath the elastic laj-er of the intima 

 and in the neighborhood of the ligature, possibly the cells may 

 have exhibited slight traces of irritation. At this date, then, 

 the plastic or cellular clot mainly consisted of an accumulation 

 of epithelioid or, more correctlj' speaking, endothelioid cells 

 and their progenj-. In the tunica adventitia, especially near 

 the ligature, and in the surrounding connective tissue a con- 

 siderable cellular increase had commenced. 



Fig. 1 represents the femoral artery of a dog twenty-four 

 hours after ligature. A transverse section just above the level 

 of the bottom of the blood-clot, which has fallen out while 

 handling, and which has not been drawn, a. Adventitia, not 

 much cellular increase at this level, c. Surrounding cellular 

 or connective tissue, showing greater increase of cell elements. 

 m. Media not perceptibly altered, e. Elastic folds of the inti- 



