30 
Transactions of the Boyal Society of South Africa. 
There seems little doubt that these after-effects are due to a process 
occurring in the nerve subsequent to the process which gives rise to the 
action current. The positive deflection is the first phase, which affects the 
proximal electrode, and is alone apparent on the curve from nerves where 
the demarcation current is of its full value. The negative deflection 
constitutes the second phase and is to be attributed to the distal electrode. 
The whole deflection is brief, and has run its course in about 5 sec. 
Although in the fresh nerve a positive after-effect only is apparent, we 
cannot exclude the possibility that the process underlying the after-effect 
Fig. 4. 
Eesponses from nerves 20 hours after preparation, without fresh section, 2 cm. between 
leading off electrodes. Curve a before cooling, Curve h after distal electrode has been 
cooled. 
occurs to some if only a small extent in the neighbourhood of the cross 
section, and that in such a record as that represented by fig. 1 the curve 
gives the algebraic sum of the two phases. 
In Garten's paper curves are published (Plate XIX., tigs. 2 and 4) from 
nerves which, at room temperature, showed well-developed positive after- 
effect, and which after cooling yielded records where this has disappeared, 
and, as Garten states, the curve returns to its zero position. As a matter 
of fact, however, careful examination of these curves demonstrates that a 
small negative after-effect of short duration is present. This may be the 
* Loc. cit. 
