DISAPPEARANCE OF RED CORPUSCLES IN THROMBI. 235 



thrombus from its very commencement, or only sprang 

 up in it afterwards, or found their way into it in some 

 other manner. Now upon accurately following up the 

 different stages of the process, the very positive result is 

 obtained that the corpuscles pre-exist, and that they do 

 not arise within the clot, and are not forced into it. Even 

 when quite recent thrombi are examined, the corpuscles 

 are found in many places heaped up in great masses, so 

 that, when the fibrine breaks up, they are set free in such 

 numbers, that the debris are nearly as rich in cells as pus. 

 It ip with this process just as when water which is tho- 

 roughly impregnated with solid particles is frozen and 

 then exposed to a higher temperature ; when the ice 

 melts the enclosed particles must of course again come to 

 light. 



To this view of the matter one objection may be raised, 

 to wit, that we do not see the red blood-corpuscles set 

 free in a similar manner. The red corpuscles, however, 

 perish very early they are soon seen to grow pale ; they 

 lose a portion of their colouring matter and become 

 smaller, whilst numerous dark granules appear at their 

 circumference (Figs. 54, a ; 70, C), and in the majority 

 of cases they entirely disappear, nothing but these gra- 

 nules at last remaining. Still there are also cases in 

 which the red corpuscles retain their integrity within the 

 softening mass. As a rule they certainly perish, and it 

 is precisely upon this that depends the peculiarity of the 

 transformation, by means of which a yellowish white 

 fluid arises bearing the external appearance of pus. And 

 for it too an explanation may be found without any par- 

 ticular difficulty, if it be borne in mind how very trifling 

 is the power possessed by the red blood-corpuscles of 

 resisting the most various reagents. If to a drop of 

 blood you add a drop of water, you see the red corpus- 



