356 



THE SENSES 



qualities to these sensations. These qualities, however, are unknown. 

 Sensations being known if anything is, this is tantamount to saying either 

 that some of these described afferent end-organs transmit inward to the 

 cord, etc., impulses which give rise to no analyzable portions of con- 

 sciousness, or that some of these organs, either directly or through nerve- 

 fibrils connected with them, represent other sensations subserved by 

 the skin: of heat, cold, pain, tickling, electricity, pleasure, or what-not. 



FIG. 208 



FIG. 209 



-d, 



"Golgi-Mazzoni corpuscles" found by Ruffini in 

 the subcutaneous connective-tissue of the ball of 

 the finger. 



Nerve-terminations in a tooth of the fish 

 Gobius: d, dentine; n, nerve-fibers. (Ret- 

 zius.) 



At present, in short, the specific duties of some of these end-organs 

 described by good observers as tactual in function cannot be told any 

 more than can their relations to each other, to the touch-pressure spots, 

 and to the brain. 



Landois showed that the finger recognizes as separate the vibrations of 

 a string occurring 1552 times per second, while induced electrical currents 

 of 130 per second are felt as disparate. The latent period and the sub- 

 sidence-period of touch-organs are then both very brief. 



