238 OUTPOSTS OF THE INTELLIGENCE SERVICE 



volar surface 



TABLE XXXIII— co;;^«me(^. 



Centre of palm ..... 



Dorsum and side of tongue ; white of lips ; meta 



carpal part of the thumb 

 Third phalanx of the great toe, plantar surface 

 Second phalanx of the fingers, dorsal surface 

 Back 

 Eyelid 



Centre of hard palate 

 Lower third of the forearm 

 In front of the zygoma 

 Plantar surface of the great toe 

 Inner surface of the lip 

 Behind the zygoma . 

 Forehead 

 Occiput . 

 Back of the hand 

 Under the chin 

 Vertex 

 Knee 



Sacrum, gluteal region 

 Forearm and leg 

 Neck 

 Back of the fifth dorsal vertebra ; lower dorsal 



and lumbar region 

 Upper arm ; thigh ; centre 

 Middle of the neck 



of back 



Millimetres. 



8-9 



-11-3 



13-5 

 15 



15-8 

 15-8 

 20-3 

 22-6 

 22-6 

 27-1 

 29-8 

 33-8 

 33-8 

 36-1 

 44-6 

 45-1 

 54-1 



54-1 



67-7 

 67-7 



The intensity of the contact sensation is increased in a mechanical 

 way by the presence of hairs, because they act as levers on the 

 tactile corpuscles. The whiskers of the cat render the touch 

 points of the jaw very sensitive in this way, being able to detect 

 even slight air currents. 



2. Tickle is a sensation that may be classed among the surface 

 phenomena like touch, or among the deeper sensibilities like 

 pressure. Dealing exclusively with the former variety, we may 

 say that the stimuli producing it are light, intermittent or stroking 

 touches applied to the surface of the body. We must again 

 distinguish between stinmlation of a surface furnished with hairs, 

 such as the back of the hand, nape of the neck, etc., and those 

 surfaces that are hairless, such as the sole of the foot, dorsum of 

 the tongue, back of the throat, etc. In the former case, even a 

 gentle touch applied to the end of a hair, 'provided it is sufficient to 

 bend the hair, gives rise to a short burst of electrical waves along 

 the sensory nerve, and adaptation occurs rapidly, i.e. the receptor 

 is of the phasic type. Histological examination shows that the 

 hair acts as a lever transmitting pressure to the tissue surrounding 

 its root, in which are embedded arborisations of sensory nerve 



