EXTRACT VII. 



ON CIRCULATION IN ITS GENERAL NERVINE BEAR- 

 INGS, AND "CIRCULATIO C1RCULATIONUM OMNI4 

 CIRCULJTIO." 



IN describing the bond of union, or connection, between 

 the circulation of the blood proper, and, what we have 

 called the cerebro-spinal, or nervine, circulation, let us 

 begin with the cerebral capillaries by which the brain 

 pabulum is laid down amid the neuroglial matrix or 

 stroma, where the true nerve elements, as neurons, take 

 their origin and grow. These vessels, by a process of 

 osmosis through their walls, exude this nutritive material 

 into the neuroglial matrix in the more or less amorphous 

 form in which the neurons, it seems to us, take it up, by 

 their dendritic processes and attached gemmules(Fig. 22), as 

 distinguished from their axonal processes and cell walls, 

 these latter being mainly insulating and protective, and 

 surrounded by peri-saccular and peri-axonal lymph spaces. 

 Within the matrix of the neuroglial tissue it seems to us 

 that the terminating peri-vascular spaces, and incipient or 

 nascent peri-saccular and peri-neural spaces, merge or unite 

 and " give and take," thus joining the peri-vascular and the 

 peri-neural lymph circulation into one " system of circula- 

 tion." In other words, we see here a circulation which 

 secures that the brain and cord and nerves are floated in 

 lymph, or fluid, that they are supported by a column of 

 fluid internally, and that the entire substance of the 

 neuroglia wherever existent, in brain, or cord, or ganglionic 

 enlargement, is inter-penetrated by the same. Thus are 

 provided support and protection, with facilities for nutri- 



