C. ESTABLE 313 



or without myelin sheaths, it is an insulation contact (Fig. i): it is not 

 known whether it is possible for a neurone to act upon another neurone, 

 through the slightest and thinnest glial sheaths. According to Dc Castro's 

 theory, the synapse might comprise three elements, the aftector, the 

 effector and the glial layer (De Castro, 1947, 195 1); our observations, 

 reported in 1952 and 1953 (one of them in collaboration with Reissig and 

 de Robertis) do not confirm the existence of the glial layer taken for 

 granted by De Castro (Estable, Reissig and De Robertis, 1954). 



V.ssyn. 



* 3»- 



Fig. 4 

 Deiidro-somatic contact. Photo-micrograph of two cells of the 

 reticular formation of the human pons. D.s. syn. shows a dcndro- 

 somatic synapse which, because of closeness of contacts, appears as 

 an anastomosis between neurones. (Cajal's silver method.) 



Functional contacts occur either between neurones or between neurones 

 and differentiated cells such as receptor cells (neuro-receptive contact), 

 secretory cells or contractile units (neurone-effector contact). Since nerves 

 and particularly axons have been studied with more attention and accuracy 

 than dendrites and the perikaryon — except as to the trophic function of 

 the latter — it is easy to realize why a certain axonism overshadows the 

 doctrinary aspects of the general physiology of the nervous system. For 

 the same reason, this axonism has been biased by the concept that the axon 



