226 



MORBID STATES OF THE BLOOD, ETC. 



vascularisation of the tlirombus begins.* This conforms to the 

 "tertiary'' type, i.e. the opening up of capillary channels along 

 the threads of the protoplasmic network. A more or less com- 

 plete vascularisation may be demonstrated in every thrombus 

 over eight days old, whether by injection, or by the examina- 

 tion of fine sections. The vessels are thin-walled capillaries 

 with alternating nuclei (fig. 71, a); they get their blood mainly 

 from the still pervious portion of the occluded vessel itself, 

 whither also they return it, until other anastomoses are deve- 



Transverse section througli a clot produced by ligature of the 

 crural artery, tMrty-seyen days after operation. Hardened in 

 alcohol. Treated with dilute acetic acid and then with a little 

 ammonia, a. Capillaries ; h. The cell-network of the colour- 

 less blood-corpuscles. In the basis-substance we see the 

 outlines of the red corpuscles. 



loped, though still in scanty number, with the vasa vasoinnn. 

 An indispensable preliminary to the formation of such anasto- 

 moses is the perforation of the non-vascular tunica intima of 

 the vessel, separated as it is from the middle coat by its homo- 

 geneous limitary membrane ; and this is clearly a harder task 

 for nature to perform than we might at first imagine it to be 

 (fig. 72). _ , 



§ 192. The vascularisation of the clot guarantees it a more 

 durable and organic connexion with the body ; it becomes hence- 

 forth a member of the series of vascular connective tissues. But 



* See 0. Weber, Handbuch der Allgemeinen und Speciellen Chirurgie, 

 redig. von Fiiha und Billroth. Bd. i., Lieferung.l, p. 143. 



