AfOTIONS IN PIAXT^S.. 
^TTj; 
By the sketch 1 have given, it may easily be conceived how Twi^tiit by 
perfectly unlike they are to bubbles of water; and, indeed, 
all that were taken for that secretion were as different in lot in 
a'f various in figure. 
1 may now turn to my last anniment, which embraces aho r«n»i.atii*n of 
, . . r I . . . . ... oil ill tin- r nil at 
the perspiration or plants. I lia\c satd, that t!ie *imal wire 
is formed of a middle vessel, which is {v,rlly filled with oil, 
which humects and lubricates the wire to pa-vent its being 
injured by friction ; but from whence could that oil come ? 
Oil is certainly to be found in many plants, but completely pure 
and adapted for the purpose. I had not, indeed, the smallest 
idea of finding it ; conceive my transport at the discovery. 
I Observing in the gatherers of the rose, the maple, and the 
. acacia, some vessels that run directly from the hairs at the exte- Vessilspassing 
rior of the gatherer to the spiral wire in the middle of it, 1 
was most curious to see what liquid they conveyetl, as I h,ad 
generally observed, that the vessel passing from these, instru- 
ments merely carried the juices within the cuticle, and thus to 
the wood where the liquid seemed to mix with the sap, or 
sometimes stopped in the bark. But I had never noticed any 
that pierced to the middle of the gatherer. What, then, could 
they convey ? It was oil, pure oil, which was received by a I’ilh'^ with 
I most curious and pointed vessel like fig. 6 , apparently received 
from the atmosphere, and entering the hair full of a clear li- 
quid, which it seemed, by its additional weight, to force down 
througii the different valves into the interior of the plant. I Fonnatiou of 
do not suppose it is oil which is first received into the inslru- 
ment from the air, but perhaps only a dense vapour or matter, 
which having, in some of its parts, a .stronger atiinity with 
the liquid already in the hair on its entrance, is decomposed, 
the part strongly attracted passes to the liquid below, while the 
oil remains, and, pressing down the second valve, enters the o 
interstices pure and unmixed. This is conjecture only, but 
it is assisted by the appearance of the hair For the first di- Extreme bcau- 
vtsion is cloudy and mixed, while the oil below is perfectly clear, *y clear- 
iicss ot the 
and thus continues passing down from valve to valve, forcing the hairs, 
liquid before it till they both enter the plant, and leave the 
interior 
