[ 2 9 8 ] 
Plants, it may be laid, have likewife 
their fecretions, prepare their different 
juices, and notwithftanding are not pro¬ 
vided with nerves or nervous fluid. The 
faculty of fecreting would then feem to be 
inherent in, and peculiar to their veffelsj 
and if fo, why fhould it not be inherent 
in the veffels of animals ? 
In anfwer to this, I fhould obferve, that 
we have not any right to draw conclufions 
from things we do not know, and that we 
can only reafon from known fads. We 
are ignorant of the ultimate ftrudure of 
plants, their fprings and mecbanifm, and 
do not know whether they have or have not 
any nerves j but we know that an animal 
has nerves, and their influence upon the 
fecretory organs is likewife demonflrable. 
Some phyfiologifts, who have been con¬ 
vinced of the reality of this influence, have 
attributed to the nerves the whole procefs 
of fecretion: this is perhaps carrying it too 
far. We mull however allow, that they 
do much in it. This 
