GIANT NEURONS OF VISCERAL GANGLION OF APLYSIA 237 



soma on its inner side, facing the neuropile; a fairly sharp boundary separates 

 the two (Fig. 2). The ghal invasion mainly coincides with the axonal type of 

 cytoplasm but in places goes beyond it, reaching halfway around the circum- 

 ference. The surface of the cell in these regions is spongy, and not only 

 increased in extent but produced into complex shapes. Whether or not this 

 has any significance for local responses is unknown. 



Careful study of osmic-fixed, Masson-stained ganglia and formol-acetic- 

 alcohol-fixed, Holmes silver-stained ganglia has failed to reveal any evidence 

 of nerve fibers ending on the cell body or the base of the axon. A large scale 

 effort to obtain successful Golgi impregnations with the help of the late 



^1 LIBRARY = 



Fig. 6. Electron micrograph prepared by Dr. Elizabeth Batham showing a large 



(5 micra) axon in cross section in a connective; glial processes have opaque fine 



textured inclusions; these and glial membranes can be followed into the axonal 



infoldings. Calibration: one micron. 



Albert E. Galigher of Berkeley gave only extremely limited pictures of 

 occasional fibers in the neuropile. In view of the abundant experience of 

 many workers with various invertebrate unipolar cells and the absence of 

 evidence contradicting this in the present case, it seems best for the present 

 to assume no synaptic endings on the soma. 



With respect to cell contacts that might explain synchronization, I find 

 httle support for the idea of soma to soma intimacy. Processes connecting 

 somata were never seen. Simple contact of two somata is impeded by the 

 glial envelope which is general though for smaller cells often apparently 



