IN THE CAPILLARY VESSELS. 175 



many little eminences by which the further passage 

 of the germs might be interfered with. The vessels 

 themselves change much in volume many times 

 during every twenty-four hours ; the canal being some- 

 times far too narrow to permit a red blood corpuscle 

 to pass, Plate XXVI, fig. 106, p. 188, while at others the 

 tube is much dilated and filled with blood. Moreover, 

 the capillaries often form loops, and sometimes little 

 diverticula may be found here and there, in which 

 particles might collect and accumulate to some ex- 

 tent, without the tube of the vessel being in any way 

 obstructed. 



The little particles of contagious matter having 

 gained entrance into the blood and arrived at the super- 

 ficial capillary, probably absorb nutrient material ra- 

 pidly. It is possible that fibrin may become coagulated 

 around these little bodies, just as if they were par- 

 ticles of pus, and the mass being too large to pass, may 

 become impacted into some part of the capillary 

 system. The large size of the white blood corpuscles 

 in very many blood diseases is also a fact not gene- 

 rally known, although of great importance, which 

 must not be lost sight of in considering this part of 

 the question ; but I cannot discuss it here. In those 

 organs in which the circulation is slowest as the 

 spleen and liver the conditions would be very favour- 

 able to the multiplication of such particles of living 

 matter, and it is probable that in some cases the capil- 

 laries in these organs are principally affected in the 



