584 



GENERAL PHYSIOLOGY 



is s&id,"per continuitatem" but through simple contact, "per contigui- 

 tatem." The end of a nerve-fibre and the end of a dendrite join 

 at their tips, but a piece that does not consist of nerve-substance 

 is intercalated betvi^een them. It must be assumed that this inter- 

 calated piece, which is to be seen only with very strong magnifying 

 powers, consists also of living substance, else it would be difficult 

 to understand how it is able to conduct the excitation from the nerve- 

 process to the dendrites. 



While there is great unanimity in the mode of union of the 

 neurons with one another, the kind of transition of the nerve- 

 fibres into the end-cells, which they innervate, or from which they 



Fig. 284. — Section through the cortex of the cerebellum of a calf. The large, branched cells are 

 Purkinje's cells. (After Schiefferdecker.) 



spring, is very various. The nerves (sensorj-) that conduct centri- 

 petally from the periphery of the body, as well as those (motor, 

 secretory, electric, etc.) that conduct centrifugally to the periphery 

 vary according to the organ in which they end. Among the 

 former there are some that end free in the skin in the form of an 

 end-bulb, without being in connection with a sense-cell (Fig. 285, 

 11). The others appear to go out directly from a sense-cell, 

 which is specially developed for the reception of the stimulus, 

 as, e.g., the rods and cones of the eye, the hair-cells of the ear, the 

 olfactory cells of the nose (Fig. 28.5, 1), etc. Among the endings 



