144 TYPES OF BRITISH PLANTS 
species of the Primrose tribe (Primula abeonica), which 1s 
sometimes to be found in our greenhouses, and gives rise 
to a most irritating rash when handled by people with 
tender skins. / 
The Nettle follows the snake’s example very closely, 
and injects a very similar poison. As one can see with 
the naked eye, it is covered with hairs, and 
under the microscope one sees that each hair has 
a very swollen base, in which the poison is stored 
by the cells beneath, which add that to their 
ordinary duty of starch-making. The hair tapers 
down towards the end, and does not end in a 
722 ia waeeaae va, 
LLL LLL 
SS 
LLLL 
———— 
LLL. 
sharp point, but in a small knob. The wall of 
the hair is carefully strengthened throughout with 
a deposit of flint, so that it may have strength to 
pierce the skin of the assailant. When touched, 
the brittle knob at the top breaks off, and leaves 
a jagged point which promptly drives its way 
through, the pressure of the touch at the same 
time forcing up the poison, with unpleasant effects 
S for the visitor, whether it be the incautious seeker 
STING OF after plants, caterpillars, or birds’ eggs, or an in- 
NETTLE, . ° ° . 
experienced browsing animal, which probably de- 
cides after the first bite that the flavour of nettle tops is 
not worth a very sore mouth. One puzzle in the matter 
is that many caterpillars are quite indifferent to the 
stings, and find the leaves a very pleasant food, hairs and 
all. If you keep either Woolly Bear or Tortoise-shell 
caterpillars, you will see them crawling placidly at one 
time or another over all parts of the plant, although it is 
true that for feeding purposes they generally go to the 
under side of the leaf, where there are comparatively 
few stings. 
Ly 
