228 MORBID STATES OF THE BLOOD, ETC. 



eighth "vveek this constitutes the basis-substance of the thrombus. 

 Moreover the original character of its constituent elements con- 

 tinues to be recognisable for a long time. In a thirty-seven 

 days' old thrombus after ligature I found the decolorised blood- 

 corpuscles so little altered in shape that their numbers entirely 

 masked the vessels and connective-tissue corpuscles ; and it was 

 only after adding acetic acid, which made the whole specimen 

 swell up violently and obliterated the outlines of the blood-discs, 

 that the network of vessels and cells became distinctly visible. 

 Then indeed its likeness to a vascular connective tissue became 

 unmistakeable ; and I do not scruple, on the ground of its 

 reaction with acetic acid, to admit the direct conversion of the 

 stroma of the blood-corpuscles into the basis-substance of con- 

 nective tissue. I may add that even after the addition of acetic 

 acid, a judicious neutralisation with ammonia rendered the out- 

 lines of the blood-discs once more distinct, so that both the con- 

 stituent elements of the thrombus, the network of cells and 

 vessels on the one hand, and the former blood-corpuscles on the 

 other, could be seen side by side (fig. 71). 



§ 193. The remaining histological alterations may be viewed 

 as a cavernous metamorphosis {see § 129) of the thrombus. It 

 used in former days to be described as a ^' sinus-like " (sinus- 

 artig) degeneration. The blood-vessels grow wider and wider, 

 while the parenchyma between them disappears and is replaced 

 by a moderate quantity of colourless cicatricial tissue arranged 

 in concentric laminae round the vessels. At a certain stage in 

 the process the cavernous structure is exquisitely apparent (fig. 

 73). The vessels continue to grow wider and the septa between 

 them thinner, until they wholly disappear and the thrombus 

 accordingly ceases to exist. 



§ 194. The softening of thrombi contrasts with their organi- 

 sation in much the same way as suppuration contrasts with 

 organisation in the case of inflammatory products. This remark 

 applies to the clinical significance, as well as the naked- eye 

 peculiarities of the process. As regards the latter, a decolorisa- 

 tion of the primarily dark-red thrombus, plays here, as during 

 its organisation, a prominent part. The colour begins to 

 fade at its centre, and the decolorisation spreads from this 

 point to the circumference ; it is associated with a certain 

 degree of condensation which is not however, as it is during 



