ABSORPTION FROM THE VENTRICLES 319 



ferrocyanide-citrate method possesses the advantage of freedom 

 from the modifying influences of cell activity; the findings with 

 trypan blue, however, in these experiments indicate the ultimate, 

 if not the total, pathway of absorption of a colloidal suspension 

 from the dilated cerebral ventricle, 



SUMMARY 



Hydrocephalus was produced in a number of kittens and 

 young rabbits by injecting a suspension of lampblack into the 

 cisterna cerebellomedullaris. Subsequently a readily diffusible 

 solution or a colloidal dye was injected into the dilated ventricles. 

 The experiments show that absorption occurs to some extent 

 from the ventricles in hydrocephalic animals and that the path- 

 way of escape is through the ependyma into the intercellular 

 spaces and finally into the perivascular spaces. The rate of 

 diffusion of a true solution (potassium ferrocyanide and iron 

 ammonium citrate) from the cerebral chambers into the brain 

 substance is fairly rapid, but that of a collodial suspension 

 (trypan blue) is somewhat slower. No observations on the rapid- 

 ity of absorption of the foreign substances into the cerebral 

 capillaries were made. No evidence of absorption by the choroid 

 plexuses was obtained. 



