BODY TEMPERATURE OF CERTAIN COLD-BLOODED ANIMALS. 5 



During a part of the work a parasitic current such as mentioned 

 by White 1 was present. This parasite was at times entirely 

 absent, or was constant during the period of experimentation, 

 but at other times varied considerably. In order to check 

 perfectly our results we finally made it a practice to determine 

 the value of the parasite, if any, both before and after each 

 reading for the determination of the temperature of a specimen. 

 The value of the parasite was determined by placing the junc- 

 tions close together in the thermostat and determining the de- 

 flection from the zero point on the scale when the couple was 

 thrown into the galvanometer circuit, the galvanometer being 

 set to register (usually) at zero when at rest. A specimen could 

 then be quickly placed upon the proper junction and the de- 

 flection due to the difference of temperature between the free 

 junction and the one within the body of the animal determined. 

 It was found to be advantageous for one person to make the 

 galvanometer readings while another read the thermometer in 

 the thermostat and placed the specimens upon, or removed them 

 from the couple. This helped to ensure constant conditions at 

 the couples and made it possible to take galvanometer readings 

 at the instant specimens were removed. 



PRECISION OF THE METHOD. 



Through a series of preliminary tests it was found that with 

 1.33 m. of manganin resistance wire introduced into the thermo- 

 couple circuit there was an average deflection of 238 mm. on the 

 scale for one degree Centigrade difference in the temperature of 

 the two junctions of the couple. These tests were made at 

 known temperatures which were read with a certified thermom- 

 eter graduated to hundredths of a degree Celsius and a Beckman 

 thermometer set for the particular temperatures under consider- 

 ation. The junctions were in each case attached to the thermom- 

 eter bulbs and the temperatures of the baths were held as 

 constant as practicable to ensure accurate determinations of the 

 electromotive force of the couple. With the value 238 mm. per 

 degree difference in the temperature of the two junctions of a 

 couple temperature determinations accurate to 0.0042 were 



1 White, Walter P., Jour. Am. Chcm. Soc., XXXVI., No. 9-10, 1914. 



