220 MULE-HUNTING EXPEDITION. 
For the first time I gather the poison-oak 
(Rhus toxicodendron), a pretty plant, that 
climbs by rootlets, like the ivy, and trails grace- 
fully over both rocks and trees. Some persons 
are most seriously affected by it, especially such 
as are of fair complexion, if they only venture 
near where it grows. It produces swelling about 
the eyes, dizziness, and fever; the poisonous ef- 
fects are most virulent when the plant is burst- 
ing into leaf. I picked, examined, and walked 
amidst the trees over which it twined thickly, 
but experienced not the slightest symptoms of 
inconvenience. Still, I know others that suffer 
whenever they come near it. Where the poison- 
oak thrives, there too grows a tuber known to 
the settlers as Bouncing Bet, to the botanist 
as Saponaria officinalis, the common soapwort. 
The tuber is filled with a mucilaginous juice 
which, having the property of entangling air 
when whisked up, makes a lather like soap. This 
lather is said to be an unfailing specific against 
the effects of the poison-oak—the poison and its 
antidote growing side by side! 
