144. Sigmund Mayer emphatically declares that in no instance has he traced a cell process developed into a dark-bordered nerve-fibre. The process, he says, may often be traced for a certain distance alongside of a fibre; but it then suddenly ceases, whereas the fibre is seen continuing its course unaltered. Still more conclusive is the evidence afforded by nerves having only very few fibres (2–4 sometimes in the frog), which have, nevertheless, a liberal supply of cells, visible without preparation. Valentin counted twenty-four cells in a nerve which had but two fibres.[175] Now although it is possible to explain the presence of numerous fibres with rare cells either as due to subdivisions of fibres, or to the fibres having cells elsewhere for their origin, it is not thus that we can explain the presence of numerous cells which have no fibres developed from their processes. 145. With regard to this observation of the cell process running alongside of the fibre, the recent researches of Ranvier may throw some light on it. He describes the cells in the spinal ganglia as all unipolar; each single process pursues a more or less winding course as a fibril, often blending with others, till it reaches one of the fibres from the sensory root. It blends with this fibre at the annular constriction of the fibre, becoming here incorporated with it, so that a T-shaped fibre is the result.[176] If this should be confirmed, it would reconcile many observations; but it would greatly disturb all current interpretations. Ranvier remarks that it is no longer tenable to suppose that the ganglionic cell is a centre, sensory or motor, receiving the excitation or sending forth a motor impulse; for if the fibril issuing from a cell becomes laterally soldered to a nerve-fibre, there is no possibility of saying in which direction this cell receives the excitation, nor in which it transmits the impulse.