Embolism. 



143 



the organ by these anastomoses or collateral communications, the 

 anaemia is likely to be only of short duration and without func- 

 tional disturbance. In many organs such collateral paths arc very 

 abundant, and in some, as in the muscles and hmgs. Ihey are so 

 numerous and of such calibre that sufficient blood is transmitted to 

 the blocked area of the artery by the ordinary collateral circula- 

 tion witliout any special effect. The blood which previously tra- 



Fig. 10. 



Femoral artery of a large dog, injected 

 three months after ligation. (After 

 Porta.) 



Fig. 11. 



Carotid artery of 

 a goat, injected 

 thirty -five months 

 a f t e r ligation. 

 (.\ftpr Torta.) 



versed the occluded vessel is of course distributed throughout the 

 permeable branches arising proximal to the site of obstruction 

 and driven into these by the arterial pressure. The blood pressure 

 in these collateral paths must therefore be somewhat raised, for 

 which reason, as well as from the probability that the ansemic area 

 actually sucks in the blood from these paths, the blood in the 

 collaterals flows with increased rapidity. This excess of pressure 

 also determines an additional! dilatation of the collateral vessels, 



