112 BOTANICAL GAZETTE [avons 
If Wresner’s conception that checking transpiration and con 
sequent accumulation of water is the cause of the development oi 
buds when the leaves are removed is correct, we should expect to 
find the same development if we occasion an equal accumulation of 
water without the removal of the leaves. But this does not happen — 
Experiments were conducted on young shoots of Salix, Populus, 
Cornus, Ulmus, Solidago, Silphium, and other plants. These need 
not be described individually, it being sufficient to say that when 
grown in the moist chambers described above, including the onein 
which the chamber was filled perpetually with fine spray, the buds 
showed no tendency to develop. In some cases cuttings were used, 
and in others plants with roots in soil or in nutrient water cultures. 
No loss of water was possible anywhere, and every part of the plant 
capable of taking in water was doing so. On the other hand, as will 
be discussed later, the buds promptly develop even when very plainly 
suffering from lack of water, if the tip of the shoot be removed. 
Roots of Taraxacum with all buds removed were left in rather 
damp air, but yet allowing a slow evaporation of water from the sub 
face. While thus slowly drying they all regenerated new buds and 
shoots. WAKKER obtained buds on leaves of Bryophyllum when 
submerged, but, as GoEBEL has mentioned, we do not know Wie 
other factors come into operation in the course of such drastic treat 
ment. One of the most striking cases of the direct influence of wale 3 
in inciting regeneration is that of Cardamine pratense, which, _ 
GOEBEL (3, p. 425) showed, produces shoots on the leaves while sill 
intact, when the plant is placed in a moist chamber. Bud primordit 
in this case are already formed on the leaves, and in their moist sh xc 
habitat in nature, where vegetative growth is luxuriant, : 
abundantly, so that here we are probably only dealing with the us™ 
precocious vegetative growth of this plant. | 
It is in the case of root production that we get what at first seems 
to be the most striking examples of the direct influence of wale 
the origin of new parts. It is well known that many stems ee 
roots when cut off and placed in water, and KLEBS, a5 mention” 
above, has shown that in Salix the application of water to local @ ie 
of the stem, without any wounding, is followed by a copious PP” 
ance of roots. But even here a closer analysis of the condition 
