86 



PHYSIOLOGY 



CHAP. 



frenulum is rich in touch spots. Mechanical excitations of the 

 gland which move the whole penis can be transmitted to and 

 perceived by the tactile points of the frenulum and prepuce ; but 

 if the gland is pinched without moving the penis, it is seen that 

 slight pressures are not noticed, and strong pressures produce 

 pain. At the edge of the prepuce, on the contrary, and on the 

 freuulum, a slight pinch does give a sensation of contact, and a 



stronger pinch causes pain. Corre- 

 sponding results are obtained with far- 

 adic stimulation. The pain produced in 

 the gland is different in character from 

 that felt in the prepuce and the skin 

 in general: it is a tearing and cutting 

 pain, which seems to arise deeper down. 

 The thermal sense also presents cer- 

 tain peculiarities in the human penis. 

 The number of thermal points for heat 

 and cold increases like the pressure 

 points from the roots of the penis to the 

 edge of the prepuce ; but in descending 

 along the inner surface of the prepuce 

 to the root of the gland thermal sensi- 

 bility increases instead of diminishing. 

 The corona is one of the regions in which 

 thermal sensibility to cold is most in- 

 tense (as in the tips of the mammae, 

 the eyelids, lips, and tongue). Passing 

 from the corona towards the mouth of 

 the urethra, this .sensibility rapidly 

 diminishes and disappears. The frenu- 

 lum and meatus alone contain many 

 cold points. 



FIG. 34.-Globuhir Rufflni's corpuscle, ^ ne CO ^ SpOtS Ot the glaild react to 



from labia minores. (stunp'iii.) adequate stimuli as well as to faradic 



n.f., myelinated nerve-tibre ; e.c.s., ,- T mi i i J_T i 



elastic sheath of connective tissue: Stimuli. J-hey aiSO ShOW the phenO- 



^heUcTbr,'? 1 '" 1 menon of paradoxical excitation in a 



remarkably acute form. Stimulation 



of the cold spots with the end of a heated metal cone produces an 

 indubitable sensation of cold, which increases as the temperature 

 of the cone is raised above the mean temperature of the body. 

 Above 50" C., however, a sensation of burning heat is associated 

 with that of cold. Owing to the great number of cold spots in 

 the corona, the contact of hot metal surfaces also produces 

 a sensation of cold that is more intense within physiological 

 limits in proportion as the temperature of the stimulating body 

 is raised. It is only around the mouth of the urethra that the 

 heat stimulus produces a sensation of warmth. Determination of 



