C. ESTABLE 33 I 



niyofibres, as far as the nucleus. We have given it the name of dxokaryo- 

 Iciiiiiial synapse. 



By calhng it axokaryolenimal we do not imply that the sarcolemma is 

 not interposed between the axolemma and the karyolcmma, but refer 

 simply to the direction of the growth cone towards the nuclei of the 

 motor plate and the apposition of the synaptic membranes to the nuclear 

 membrane. 



The question of the trophic function of the synapse may also be men- 

 tioned. When synapses are already modelled, the neuronal trophism 

 depends so much on them, that the neurones may atrophy and die if the 

 former are suppressed. When speaking of the polarization of the nervous 

 impulse, no account is given, besides the new synaptic types we have 

 described, of the trophic function of the synapse, whose direction is the 

 same as the direction ot the propagation of the excitatory state — oscillo- 

 graphically registrable — or the reverse. By means of the trophic function 

 of the synapse we might account for the existence, within it, of mito- 

 chondria and perhaps microvesicles, and, as far as the neuromuscular 

 synapse is concerned, for the abundance of nuclei in the sole. 



To sum up our thesis: 



It is unanimously recognized that in the normal activity of the neurones, 

 the excitatory or inhibitory state starts from dendrites or somata, the 

 excitation coming from a sensorial cell or another neurone. It is also 

 known that the dendrite is receptor and conductor, while the axon is triins- 

 initter and effector, whether it ends on anotlier neurone, on a myofibre or 

 in a crniocyte. 



The rigidity of our conceptions concerning inter-neuronal relationship 

 contrasts with the functional plasticity of the nervous system, particularly 

 well illustrated in the study of learning. The new contacts we have 

 described extend this way of thinking. Dendrites, perikaryon and axon 

 may normally fulfd the three mentioned functions; that of reception, 

 conduction and efiection. The axon woulci be receptor and conductor in 

 the cone of origin (axon hillock) receptor, conductor and effector in the 

 parasynapses; and effector in the axo-dendritic and axo-somatic synapses. 

 The dendrites would be receptor, conductor and effector in the dendro- 

 dendritic synapses (perhaps in the dendro-somatic synapses also), and only 

 receptor and conciuctor in the axo-dendritic and axo-somatic synapses. 

 The soma or perikaryon would be receptor, conductor and effector in the 

 soniato-somatic synapses (perhaps in the dendro-somatic synapses 

 also). 



