WALTER E. GARREY 



151 



distinct chemical changes seemed likely from analogy with a stretched 

 striated muscle — which increases its osmotic pressure,^-^ and pro- 

 duces excess of both lactic acid^ and C02.^ 



To determine the rate of CO2 production by the cardiac ganglion 

 when stretched, silk ligatures were attached to either end of the 

 nerve cord and looped over hooks on the glass mounting rod. By 

 means of these threads it was possible to stretch the ganglion re- 

 peatedly, increasing its length some 20 per cent of normal, without 

 apparent injury. The rates of CO2 production before, during, and 

 after the stretching in five experiments are given as averages in 



TABLE I. 

 Faradic Stimulation and Rate of CO2 Production. 



Table II. That the increase during stretching is not merely a re- 

 sult of increasing surface for diffusion, is indicated by the persistent 

 increase in the rate of CO2 production after the stretching operation 

 had stopped. It is due to the mechanical stimulation of the respira- 

 tory rate; and the results thus run parallel to the increase in the 

 rate of heart beat when the ganglion is similarly stretched. 



» Cooke, E., 7. Physiol, 1898, xxiii, 137. 



• Garrey, W. E., /. Bicl. Chem., 1909, vi, p. x. 



T Gotschlich, E., Arch. Physiol., 1894, Ivi, 355. 



•Eddy, N. B., and Downs, A. W., Am. J. Physiol, 1921, Ivi, 188. 



