( 425 ) 
Also one of the leaves, mentioned above, in which a small cross- 
wound was made in the middle piece and at the same time in the 
first piece (as in fig. 1), showed a phenomenon which Lean only 
explain in this manner. It was pointed out already that above wounds 
new rootlets are regularly formed; we shall hereafter describe the 
phenomena preceding the formation of the rootlets, phenomena which 
always make themselves felt in a basipetal direction. These preli- 
minary phenomena now appeared in that leaf in the first part (1) 
above the small wound, as usual, and in the middle piece also 
above the small wound. If the polarity of this whole piece had been 
reversed, these changes should have appeared there below the small 
wound. Now this indicates, in my opinion, that the reflected impulse 
was localised and had no influence on the lateral part of the middle 
piece, after it had been withdrawn from its direct action, and 
this piece, having retained the old impulse, reacted therefore as 
normally. 
After I had succeeded in “reversing” a current, it was probable 
that it would also be possible to cause a whole plant to develop 
inversely. 
When, however, this experiment was made in such a way thata 
whole plant, with rhizome and rootlets, was reversed and the leaf- 
tops were buried in mud, it gave no result; for seven weeks such 
a plant remained absolutely unaltered; only the top of the leaf 
became white on account of tbe loss of chlorophyl-grains, caused 
by the darkness, while the rhizome grew a little and made some 
new rootlets. 
Cut leaves, freely suspended upside down or planted with their 
top in mud, gave quite different results, however. 
Nearly all the leaves, and especially and most quickly the youngest, 
first formed new rootlets, which also in this position of the leaf always 
arose at the end of the stalk ; very many appeared already after two days. 
After that several prolifications appeared generally in various 
places, and then a first consequence of the reversion could be observed 
in the course taken by the stream-bundles coming out of the proli- 
fications and continuing their way through the old leaf. 
In a cut but erectly planted leaf these go always, without exception, 
to the base of the leaf; here in nearly all prolifications the greater 
part of these currents went to the base also, but some of them took 
their course towards the top of the leaf, without reaching it however. 
Gravity, acting in the opposite direction during their formation and 
development, had evidently deviated them. 
Stull more clearly the existence of an antagonism between gravity 
