436 



EDWARD HORNE CRAIGIE 



constant. The distribution of the blood, on the other hand, 

 may vary in different physiological states, the greater part being 

 in the arteries under certain conditions, in the veins and capil- 

 laries under others. The pressure may vary very widely, and 

 is not necessarily the same as in other parts of the vascular 

 system. The cerebral venous pressure and the pressure in the 



Vascularity 



Parkt of &ra." 



Chart 1 Graph showing the relation of the vascularities observed in material 

 fixed in Bouin's fluid (Toronto animals only) and in material fixed in 10 per cent 

 formalin. The break separates white and gray matter. Material fixed in Bouin, 

 + ; in formalin, • Numbers of regions as in chart 2. 



capillaries are always the same, however. A very careful rein- 

 vestigation in collaboration with Macleod ('01) merely confirmed 

 Hill in his previous conclusions, in spite of the histological evi- 

 dence of the presence of nerve fibers on intracranial vessels which 

 had been brought forward by Huber ('99) and others. According 

 to Corin, 2 the circle of Willis decreases the pressure of the blood 

 before it reaches the brain. 



1 Cited by Stopford, quoting Poirer and Charpy's Traite d'anatomie. 



