252 BOTANICAL GAZETTE [OCTOBER 
, Tesult is the same if both leaves of specimen 3 are partly sub- 
mersed in water; both form roots and shoots in that case. 
According to the idea that isolation is the cause of regeneration, 
we should say that leaf 1 formed new roots and shoots because 
it was completely isolated; that leaf 2 did not do so (for a long 
time at least) because, being connected with a piece of a stem, it 
was less isolated. But leaf 3, which was still 
less isolated than leaf 2, inasmuch as it had 
another leaf attached to the stem, formed roots 
and shoots much more quickly than leaf 2 
and often almost but not quite as quickly as 
leaf 1. The idea that isolation is the cause of 
regeneration is obviously inadequate in this 
case. 
Figs. 4 and 5 are a repetition of this experi- 
ment. The two leaves had been submersed in 
water for 5 weeks. The leaf in fig. 4, with a 
piece of stem attached, 
had formed no roots or 
}s shoots in its notches; in- 
stead it had formed a long 
shoot (S) from the bud of 
the stem opposite the leaf. 
The leaf in fig. 5, with a 
piece of stem and the 
opposite leaf, had formed 
four shoots from the sub- 
mersed notches, while the 
\ stem had formed one tiny 
Fics. 1-3 shoot (S) from a bud in 
the axilla of the lower 
leaf, and roots (R) at the under side of the basal end of the 
stem. 
When we modify this experiment and suspend the three leaves 
entirely in moist air (instead of submersing them partly in water), 
leaf 1 (entirely isolated) will again form roots and shoots in its 
notches; leaf 2 will as a rule show no growth, but from the opposite 
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