358 



PHYSIOLOGY 



CHAP. 



Patrizi instituted numerous plethysmographic researches with 

 the object of determining the exact vasomotor reflex tissues in the 

 arms, legs, and brain of man, when awake, when asleep, and under 

 various other conditions. Besides confirming certain general laws 

 for reflexes, in the vascular regions, Patrizi found that the vascular 

 reflex times, which are fairly equal in the waking state, for the arms 

 and legs, with a slight advantage on the side of the upper limbs, 

 undergo in the latter a considerable delay in sleep, whereas the reflex 

 time for the lower limbs remains constant. During sleep the 

 reflexes are most delayed in the cerebral vessels. 



Patrizi and Cavani also detected a right- and left-handed 



FIG. 164. Reflex pressure effect on excitation of rabbit's skin at E. (Tigerstedt.) Carotid con- 

 nected with Ludwig's kymograph. Time tracing from an electric signal, along the abscissa, 

 in seconds. 



vasomotor asymmetry in man, to which they attributed a more 

 rapid and pronounced vasomotor reaction, in one as against the 

 other half of the body. 



This superiority of vasomotor functions usually obtains in that 

 half of the body which shows itself most capable of muscular force. 

 The time gained in the vascular reflexes in the favoured half of 

 the body may amount almost to one second. 



In all probability the vasomotor asymmetry is due to the 

 greater permeability of the nerve paths in the better exercised limb, 

 which does not exclude the possible influence of the varying 

 sensory excitability in the two halves of the body, and in the two 

 corresponding sides of the brain. 



These reflexes not infrequently occur in the vascular regions 



