On the evidence available, the dark cells are considered as active ones and the light cells as those that have failed to establish functional projections, inactive, dying, dead or degenerating ones. Cell death is most prominent and common among the small as well as the medium sized ones; probably it is during these stages of cell growth, the peripheral and central processes of axons begin to grow from the cell body and attempt to get established in their projection fields. It is strange that the ganglionic volume is the greatest on embryonic day 18 (E18) during the whole ontogeny even though its rostrocaudal length is greatest in the adulthood, unlike other ganglia studied in which the ganglionic volume is the greatest in the adult situation. The reduction in the size of the adult ganglion and in the number of its neurones might indicate a functional reduction, as a result of ageing process. Probably the larger classes of cells that have appeared in certain stages of development and growth are functionally unimportant or redundant in this ganglion and are eliminated in the adult situation.