314 PROPERTIES OF THE COLLOIDAL CONSTITUENTS 



microscope, rhythmic contractions will be seen travelling in rapid 

 succession from the upper to the lower end of the intestine. On 

 touching the intestine at about the middle point with a finely pointed 

 camePs-hair brush wetted with M/6 calcium chloride solution the 

 rhythmic contractions in the affected area are immediately suppressed, 

 but on following a wave of contraction with the eye as it enters this- 

 area and disappears, it can be seen to re-issue below the affected area 

 at the moment when it would have appeared, had the contraction 

 actually traversed that section of the intestine. Evidently, while the 

 contractile function has been suppressed, the conductive functions of 

 the tissues are still unimpaired. If, however, the middle part of 

 the intestine is touched with potassium chloride solution instead of 

 calcium chloride solution, both conduction and contraction are sup- 

 pressed and rhythmic contractions remain confined to the region above 

 the affected area, the region below remaining quiescent. Conduction 

 and contraction are therefore very diversely affected by these inorganic 

 salts. 



EFFECTS OF REMOVAL OF CALCIUM FROM THE TISSUES AND 



TISSUE-FLUID. 



We have seen that an increase in the Q-* ratio in excised muscular 

 tissues leads to hyperirritability of the tissues and that the ratio may 

 be increased in either of two ways, namely by increasing the concen- 

 tration of the Sodium Ions in the environment or by decreasing the 

 Calcium Ions by employing a salt of which the acid component either 

 precipitates calcium or forms a sparingly dissociated compound with it. 



The effects of injection of calcium precipitants such as citrates, 

 oxalates, fluorides, tartrates, oleates and other soaps, etc., are very 

 widespread and fundamental. They are traceable to muscular, ner- 

 vous and glandular tissues. In small doses whether taken by mouth 

 or injected intravenously, they act as Cathartics, inducing enhanced 

 peristalsis and the evacuation of fluid f eces. In larger do ses we obtain, 

 in addition to purgation, peripheral twitchings, i. e., irregular involun- 

 tary contractions of the muscles of the extremities. An effect upon 

 the renal epithelium is also evidenced by a marked Diuresis, or abnormal 

 volume and dilution of the urine. In still larger doses a very curious 

 complex of symptoms is elicited. Shortly after the injection of massive 

 doses of sodium citrate subcutaneously in rabbits, peripheral twitch- 

 ings occur which are rapidly succeeded by convulsive movements and 

 marked disturbances of equilibrium. The forelegs are stiffly extended 

 and continually shuffling forward with a motion resembling an effort 

 to maintain equilibrium upon a slippery or moving surface. The head 

 is thrown back and the jaws are continuously chewing. Not infre- 

 quently the animals throw themselves into backward somersaults. 

 Exactly the same effects, without the peripheral twitchings, purgation 

 or diuresis, are obtained if, instead of administering massive doses to 



