LESSON XLIX 



EXCRETION (Continued) 



SECRETION OF SWEAT. BODY TEMPERATURE 



1. Sweat Nerves. Anesthetize a cat and maintain the anesthesia 

 until the animal has been killed by an overdose of ether. Expose the 

 sciatic nerve, apply a ligature, and cut centrally to the ligature. Stimu- 

 late the distal end of the divided nerve with a quickly interrupted current 

 of moderate intensity. Observe the beads of sweat collecting upon the 

 pads of the feet. Take the rectal temperature of this animal. Apply 

 a cloth moistened with warm water to the upper part of its body, 

 thereby raising its body temperature. Sweating is also evoked by this 

 means. Explain its purpose. 



Expose the external jugular vein and inject 3 milligrams of atropin 

 sulphate. Note that the stimulation of the sciatic nerve now remains 

 ineffective. The atropin paralyzes the secretory nerve endings. 



Inject 10 milligrams of pilocarpin. Sweat will again be secreted, be- 

 cause this agent excites the cells of the sweat-glands directly. Kill the 

 animal by an overdose of ether. 



2. Sweating in Man. Procure a piece of paper sensitized with 

 silver nitrate. Cleanse the palm of the hand and after a certain interval 

 apply the paper to this surface. The orifices of the sweat-glands will 

 be marked upon the paper as spots of silver chlorid. Apply to this 

 area a small pad of cotton moistened with a 1 per cent, solution of atropin 

 sulphate. Repeat the aforesaid test. Since atropin paralyzes the end- 

 ings of the secretory nerves, this test will now remain negative. 



3. Body Temperature. Determine the body temperature of the 

 subject by means of an ordinary thermometer, the bulb of which is 

 placed beneath the tongue. Ask the subject to close the lips. Observe 

 the rapidity with which the temperature becomes constant. How long 

 a time must the thermometer be left in situ before the mercury remains 

 stationary? 



Determine the axillary temperature in the same manner. Compare. 



Place the bulb of the thermometer in the palm of the closed hand. 

 Read the temperature. Compare. Wrap the hand in a thick woolen 

 cloth. Why is the temperature now higher? Place the same hand in 

 water of 20 C. for thirty seconds. Again determine its temperature. 

 Explain the result. 



Request the subject to make thirty flexions of the arms and legs. 

 Quickly determine the body temperature. For how long a time does 

 the rise persist? 



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