154 RELATION OF RESPIRATION TO RHYTHM 



shown that one can get an increase or a decrease in the respiration of 

 Bacillus suhtilis depending upon the concentration of NaCl employed. 



Adrenalin Chloride. — ^Addition of one drop of adrenalin chloride 

 solution (1 part to 10,000 parts of solvent) to each cubic centimeter of 

 the standard sodium-calcium solution stimulates the ganglion and 

 increases the heart rate^. Experiments with three gangha immersed 

 in this concentration of the drug gave the average rate of CO2 pro- 

 duction as 204 per cent, 194 per cent, and 166 per cent of the normal. 



These experiments amply justify the generalization that those 

 stimuli, which acting on the cardiac ganglion to cause an increase in 

 the rate of the heart beat, likewise produce changes which result in 

 a marked increase in the respiratory processes within the nerve 

 cells. Impulse formation by the ganglion, and CO2 production are 

 therefore intimately related processes and appear to stand in relation 

 of effect and cause respectively. A complete justification of this 

 postulate requires that we shall be able to establish a quantitative 

 correspondence between the processes of impulse formation, that is 

 rate of heart beat, and the rate of CO2 formation. Experiments 

 directed to this end could not be conducted in such a way as to re- 

 cord both the rate of heart beat and the rate of CO2 production on 

 the same preparation simultaneously, but it was possible to secure 

 a satisfactory approximation by taking advantage of the character- 

 istic effects produced by changes of temperature especially the effects 

 of transient exposure to relatively high and low temperatures. These 

 are considered in the following paragraphs. 



Effects of Temperature Extremes {Transitory Exposures). 



Reference has been made in previous communications^-^ to the fact 

 that if the ganglion is exposed for a few minutes to a very low tem- 

 perature (0°C.) and then warmed to 10°C., for example, a new rate 

 of rhythm is established which is faster than was obtained at 

 this temperature before cooling. This increase in rate may amount 

 to 25 per cent or 30 per cent. A similar effect upon the rate of car- 

 bon dioxide produced by the ganglion has been noted under like 

 treatm.ent, and eight examples have been referred to in Tables I and 

 II of a former paper.- In four experiments more recently carried 

 out the times required for the color change in our indicator at 10°C. 



