The electrical phenomena accompanying secretion. 



ii':; 



The electrical effect begins distinctly before the actual secretion x ), it 

 also reaches its maximum before the latter, and further it travels more 

 rapidly in the first part of its course. The electromotive force of the 

 chorda -variation differs with the mode of leading off, and with the 

 condition of the gland (whether it has been exhausted by repeated 

 stimulation and the like). Atropine in doses of 5 mgrms and upwards 

 abolishes the main phase of the chorda- variation in from 2—3 minutes 

 after its injection into the pleura. In those cases in which this phase 

 only is present it generally happens that after such a small dose of 

 atropine as 5 mgrms a second phase is seen, i. e. surface of gland 

 positive to hilus. This is well shown in the following experiment: 



Feb. 26. 1885. Dog, mediumsized. Crura cerebri divided. Curarized. 



Time 



Nerve 



Distance 



of 



secondary 



coil 



Duration 



of 

 excitation 



Electrical 



condition 



of 



gland surface 



Extent 



of 



galvanometer 



deflection 



3.15 



chorda 



50 millimet. 



10 seconds 



negative 



Off the scale 



3.50 



5> 



100 „ 



JJ 



J» 



» 



4.24 



)> 



50 „ 



5J 



j> 



» 



4.25 



Ten mil 



igrams of atropine injectée 



L into the pleural cavity. 



4.27 



chorda 



50 millimet. 



10 seconds 



positive 



40 divisions 

 of scale 



4.29 



)> 



— 



» 



?> 



» 



In this experiment it is seen that the chorda is giving the usual 

 effect, but that after the atropine a distinct but small second phase 

 is observed which was not seen before, owing to the large amount of 

 the first, or main phase 2 ). 



The second phase, although ultimately abolished by atropine, is 

 more refractory than the first or main phase. In appears to be pre- 

 sent nearly always even when the first phase only is observed, for 

 after this has been abolished by atropine, a deflection in the oppo- 

 site direction is usually seen. 



*) At least before any secretion appears in the duct. 



2 ) In small dogs as little as 2 mgrms of atropine is sufficient to abolish the 

 first phase of the chorda -effect, but 5 mgrms is always sufficient. 



