Pycemia and Septicemia. 21 



further the coagulation of the fibrine, and again when they come in 

 contact with the intima, instead of passing through, or moving on, 

 they remain adherent and start the formation of thrombi. This 

 is above all common in given tissues, and the medulla of bone 

 has in this respect a bad preeminence, so that acute suppurative 

 osteomyelitis, is a familiar lesion and is liable to become chronic, 

 and determine distant abscesses and general infection long after. 



The thrombus thus formed is an infective coagulum, tending 

 to constant encrease, as the clot is a favorable culture-field for 

 the microbes, and the tendency is to coagulate more and more of 

 the adjacent blood. It tends further to disintegration, as the 

 action of the microbes and their toxins on the leucocytes, trans- 

 forms these into pus cells, inducing softening of the mass, and 

 the washing on of individual infective pus cells and minute por- 

 tions of the clot to form infective centres and abscesses at distant 

 parts. 



If the pathogenesis of the invading microbe is weak and the 

 resistance of the leucocytes potent, such clots may remain cir- 

 cumscribed or may even be absorbed, but in the opposite conditions 

 with potent and numerous microbes and abundant and effective 

 toxins, the tendency is not only to a continuance of infection, 

 but to an acute febrile pyaemia. 



Pyaemia does not supervene at once upon a trauma as may 

 septicaemia, but only after a variable number of days, (3 to 8), 

 a peculiarity which is explained by the temporary protection of 

 the clot. By the constant accretions on its exterior, of the new 

 layers of haematoblasts and fibrin, the microbes are at first impris- 

 oned, and it is only when softening has taken place, or when the 

 coagulum has extended into the free flowing current passing into 

 a colateral trunk, that the infection is liable to be washed on in 

 dangerous amount. 



The mere presence of pus microbes or their toxins in the blood, 

 does not determine pyaemia : a modification of the intima of the 

 vessels leading to local infections with thrombosis or embolism 

 and abscess is an essential condition. This lesion of the vessels 

 may be a trauma, as from bruise, puncture, operation, ligature, or 

 it may be the extension of a disease process as in arteritis, phle- 

 bitis, atheroma, the growth of a tumor from adjacent tissues, or 

 parasitism. The seat of the secondary abscess depends primarily 

 on the location of the original suppurating centre. As such centres 



