THE MOVEMENTS OF ORGANISMS 298A 



of the lactic acid to CO 2 furnishes the heat which restores some of 

 the lactic acid to its metabolic source, thus removing the acid ions 

 from the colloidal fibrils, so that they may return to their former 

 tension the tension of rest or relaxation and possessed of their 

 inherent potential. Proceedings of the Royal Society of London, 

 Series B 69, Vol. LXXXIX, p. 444 et seq. 



Contraction of the heart is a special instance of muscular function 

 upon which considerable light has been thrown by the studies of 

 W. BURRIDGE. 



He views excitation as a coagulative change induced through the 

 formation of a calcium compound. According to MACDONALD this 

 coagulative change is accompanied by a release into aqueous solution 

 of previously adsorbed K salts which now confer a positive charge on 

 the colloids whence they came. This electric charge in its turn reverses 

 the coagulative change in the colloids and so brings conditions back 

 towards the original state. BURRIDGE has shown that the positive 

 charge renders cardiac colloids incapable of combining with Ca and 

 can decalcify them just as well as does oxalate, and that Na ions 

 may be a factor in determining a finer state of subdivision of these 

 colloids. Inhibition resides in the inability of the colloids of the 

 inhibited tissue to combine with Ca. 



BURRIDGE found two modes of reaction of the heart when exposed 

 to the influence of drugs. One effect, immediate in appearance on 

 application and in disappearance on withdrawal, he ascribes to " sur- 

 face" phenomena involving the muscular colloids. The other he 

 calls " deep " changes on the assumption that they involve changes 

 in aggregation or of chemical composition in the same colloidal bodies 

 in which changes of the first type take place. 



Calcium has a surface and a deep action on the heart. BURRIDGE 

 measured the response of the perfused heart to solutions containing 

 different concentrations of calcium in the presence of different sub- 

 stances. He found that digitalis caused the heart to act as well with 

 a weaker solution of calcium, as it did with a stronger solution of 

 calcium in the absence of digitalis. Barium was an imperfect sub- 

 stitute for calcium. Adrenin and pituitary extract act like digitalis 

 in improving Ca utilization. Alcohol, chloroform and ether have a 

 two-fold action, (a) A depress : ng or surface action associated with 

 poor utilization of calcium; (6) a favoring or deep action associated 

 with an improved utilization of calcium. 



Strychnine improves Ca utilization thus diminishing inhibition. 

 Dibasic potassium phosphate increased the result from a given per- 

 centage concentration of Ca. This latter is evidently an adsorption 

 phenomenon as it is maintained by adding a smaller percentage of the 



