Hemorrhage. 



121 



inatic exudate ; because of their elasticity these corpuscles are 

 easily able to pass through the most minute clefts of the cement 

 substance. There exist therefore in these cases minute micro- 

 scopic tears. Haemorrhage by diapedesis, however, may assume 

 important proportion and may be fatal because of its location (as 

 in the brain or stomach) or of its duration. 



Since it is the bathing of the endothelium with nonnal 

 blood which is essential to its integrity, it may be easily appre- 

 hended that even a temporar\- interruption of the circulation to 





FU 



1. 



Mesentery of the dog. (a) IliPmoirhago by diapedesis. (b) Ecchymosis 

 occurring in a similar manner, tlie opening in the wall of the cajiillary 

 having closed up again. The figure aU-o t-.hows an emigration of leucocytes. 

 Magnified 2.50 times. I After Thoma. ) 



the capillaries may render them abnormally permeable and be the 

 cause of diapedesis after restoration of the flow (cf. oiibolisDi). 



Haemorrhages are also classed according to the type of vessel 

 from which the blood escapes, as arterial, z'enous and capillary 

 hcemorrhagcs ; where the blood oozes from a widely diffused fault 

 in the softer tissues, as in the liver, and the type of the bleeding 

 vessel cannot be made out, the term parenchymatous hcemorrhage 

 is appropriate. 



The blood may escape freely to the exterior of the body or 



