702 



A MANUAL OF PHYSIOLOGY 



other function there is not the slightest proof), peripheral nerves 

 may be classified as follows : 



Centripetal 



or afferent 



fibres 



Centrifugal 

 efferent- 

 fibres 



or 



-Smell. 



1. Nerves of special sensation- 



ISight. " 



Touch (light touch). 

 Pressure (perhaps in- 



2. Nerves of general sensation-' muscubr^enser 8 f 



Warmth Cold. 

 I Pain. 

 r Calibre of small arteries 



(pressor, depressor). 

 Action of heart. 



those included under T Respiratory 

 and 2, concerned : 

 reflex changes in 



3.* Possibly nerves other than 



move 

 ments. 



Visceral movements. 

 Glandular secretion. 

 Ordinary skeletal 



muscles. 

 Skeletal muscles 

 Visceral 



( Vaso-constrictor 

 Vascular j Cardio - augmen- 



( tor. 



Erector muscles of hairs (pilo- 

 motor fibres), 

 r Visceral muscles 



2. Inhibitory nerves forj fVaso-dilator. 



(Vascular ,, - Cardio -inhi- 



3. Secretory nerves I bitory. 



i. Motor nerves for 



* It is not known whether the afferent portion of a reflex arc is always 

 composed of fibres included in the first two categories, although un- 

 doubtedly in some cases it is. 



PRACTICAL EXERCISES ON CHAPTERS IX. AND X. 



i. Difference of Make and Break Shocks from an Induction 

 Machine. Connect a Daniell or other cell B (p. 615) with the two 

 upper binding-screws of the primary coil P, and interpose a spring 

 key K in the circuit. Connect a pair of electrodes with the binding- 

 screws of the secondary coil (Fig. 258). 



Electrodes can be very simply made by pushing copper wires 

 through two glass tubes, filling the ends of the tubes with sealing- 

 wax, and binding them together with waxed thread. The projecting 

 points may be filed, and the nerve laid directly on them, or they 

 may be tipped with small pieces of platinum wire soldered on. 



(a) Push the secondary away from the primary, until no shock can 

 be felt on the tongue when the current from the battery is made or 

 broken with the key. Then bring the secondary gradually up 



