ELEMENTARY EXPERIMENTAL PHYSIOLOGY 9 



(If a case of disease of the spinal cord with dissociated sensibility 

 is available, it should be used to demonstrate the conduction from 

 the three kinds of receptors in the skin by separate tracts in the 

 cord.) 



Lesson I. To be provided for the Class. 



1. A small vessel of mercury. 2. A cogged wheel of about 5 inches diameter, 

 with 100 teeth on the circumference, driven by a small motor and with a 

 resistance to vary the speed. 3. A couple of microscopes with sections of 

 skin to show tactile corpuscles and hair follicles. 



To be provided for each pair of Students. 



1. Some brush bristles of different strength fitted transversely in split 

 wooden matches. 2. A very fine steel needle. 3. A small piece of cotton 

 wool. 4. Six small flat pill boxes loaded with shot to weigh about 4-6-8-10- 

 12-14-16-18 gins., and filled up, closed and sealed with paraffin wax. Each 

 should have a distinguishing mark on the bottom, corresponding to a similar 

 mark upon a card with the weight marked upon it for reference. 5. A pair 

 of fine pointed compasses and a millimetre scale. [NOTE. There is a milli- 

 metre scale on the induction coil.] 6. Three basins and a supply of hot and 

 cold water. 7. A piece of metal. 8. A metal rod with a fine point. 9. A 

 thermometer reading to tenths of a degree Centigrade. 10. Two large test 

 tubes. 



LESSON II 

 TASTE 



Revise the anatomy of the tongue, and examine with a micro- 

 scope sections of the foliate papillae of the rabbit's tongue to see 

 the structure of the taste-bulbs. 



Is the Sensibility to Taste the same all over the Tongue ? 



METHOD. Solutions of (1) sugar, (2) quinine, (3) hydrochloric acid, 

 (4) common salt, are provided. One student rinses out the mouth 

 with water, and another applies, with a camel's-hair brush, one or 

 other of the solutions to some part of the tongue and notes the 

 sensation which is said to be produced. The tongue must be kept 

 protruded whilst the taste is being determined. The mouth is again 

 rinsed and the process repeated, and thus the various parts of the 

 tongue are investigated for their sensibility to the different sub- 

 stances. The results should be recorded as a diagram. 



Is the Sensation of a Specific Nature? 



(a) Tap gently the tip and other parts of the tongue with a clean 

 glass rod and note the nature of the sensations. 



(6) Place the free ends of two wires connected with a Daniell cell 

 or the galvanic terminals of the switch board upon the tongue, and 

 record the sensations produced at the anode and kathode respec- 

 tively at make and break of the constant current. 



