BLAZE-CURRENTS OF VEGETABLE TISSUES. 39 
been aroused by a shock in the opposite direction, with the 
kathode at the dorsal surface. 
From these points I provisionally infer that the dorsal surface 
of my fungus is more excitable (leistungsfähig) than the ventral 
surface, and that the exciting current has been more effective at 
the anode than at the kathode. But we had better not go off 
into a discussion of this point now. 
$14. I take a leaf of hart's-tongue, lay it on its face, and lead 
off from its dorsal surface by the electrodes A and B applied to 
the midrib 4 or 5 centimetres apart. The trial comes out as 
follows :— 
mm 
1/100 volt........... essen 20 
Exe. by break 100004 ................ esse 1004- 
» » — eee eene 80-- 
Strong tetanisation. 
Exe. by break 100004 ................. se. trace-+ 
» » LEM nil 
1/100 volt.................. eese 30 
Three points are seen in this experiment: (1) that this leaf 
manifests strong homodrome blaze-currents; (2) that these 
eurrents are abolished by strong tetanisation; and (3) that the 
resistance has been considerably reduced. 
$15. And now, again, questions press upon us. Is the effect 
of tetanisation temporary or permanent? Will a leaf give a 
succession of blaze-currents of diminishing or undiminishing 
magnitude? What relation is there between strength of 
excitation and strength of blaze? What are the time-relations ? 
What is the cause of the diminished resistance ? 
All these questions clamour for their answers ; but they must 
wait. 
$ 16. The next object I undertook to test was some duckweed. 
The results of its trial are as follows :— 
1/100 volt through electrodes. 
» ” n and a leaflet. 
Blaze after break-shock 10000-4 ............ is + 
LE "n LE LCLLLLLLLLLTTLITT 
After strong tetanisation :— 
Blaze after break-shock 10000+ .......... 4 oni 
1 2» 305 0000000 cs99538859835 959 
It is not a convenient plant to work with, because the leaf is 
so small. I try whether a mass of overlapping leaves give blaze, 
and find that they do not. 
