230 
Transactions of the Royal Society of South Africa, 
paper, the electrical change under one electrode produced by the passage of 
a peristaltic wave in the ureter is similar in form to Fig. 7, then we may 
interpret it on the lines that two or more processes are evoked almost 
simultaneously under the one electrode, whose electrical expressions interfere. 
The initial downward Q would indicate on this view that there is a process 
evoked tending to depress the curve, with a shorter latent period than 
another process which tends to elevate the curve. 
