310 



BRAIN MECHANISMS AND LEARNING 



medium might move about. As neurones lack any direct contact with 

 capillaries, except for the ones which they innervate, their nutrition is 

 ensured by aiK^iooUocytcs. Furthermore, there are neither anastomosis nor 



***/-..^ - V 



gl inv -* 





gl. capsule. ji .'*^ 



Fig. I 



Insulation contact between neurone and glial cell. Electron-micrograph of a nerve cell belong- 

 ing to a ganglion o{ Xyleiis fiiscipeiniis (Brunner) Gistel (orthoptcra) gl. inv. shows tlnger-like 

 processes of glia cells penetrating the perikaryon of a neurone and thus establishing a close 

 'insulating' contact with the neurone. No fusion or perforation of the cell membrane exists. 

 G. = Golgi components; m = mitochondria; gl. = glial capsule. 



loose ciui< in the nervous textures. All interactions occur by contact 

 between membranes, with or without invaginations, the membranes 

 being either of the same or of different natin-c. The tu-st requirement, in an 



