376 Marvels of the Universe 
Stinging Nettle being mimicked by the White Dead- 
nettle and the Nettle-leaved Bellflower. Here the 
advantage to the mimicking species is very evident. 
The Stinging Nettle, by reason of its stinging hairs, 
is avoided by all browsing animals, and, therefore, it 
is a distinct advantage to other plants to be mistaken 
for it and left alone. The Stinging Nettle has incon- 
spicuous green flowers that hang in strings from the 
upper parts of its stem. The Dead-nettle is entirely 
unrelated to it, and has large conspicuous white flowers ; 
but until these appear anybody but a botanist would 
accept the plant as a Stinging Nettle, and avoid it 
accordingly. To make the resemblance more effective, 
the Dead Nettle selects as the place of its growth 
similar situations to those affected by the Stinging 
Nettle—field borders and waysides chiefly. Not merely 
so, but it will often be found actually mixed up with a 
colony of Stinging Nettles. 
In the case of certain succulent plants the mimicry 
is of inanimate things—stones to wit. The photo- 
graphs show two species of Mesembryanthemum—allies of the little Ice-plant of our con- 
These plants, like other succulents, grow in hot dry situations, where vegetation is 
rare and eagerly sought after by herbivorous animals. Instead of protecting themselves as the 
Cacti do under similar conditions, by developing a hedgehog-like panoply of spines, they have 
hit upon a simpler plan: that is, to get themselves up in the likeness of pebbles and rough frag- 
Our examples have been photographed in the midst of such material to show what 
admirable cases of mimicry they are. Of course, when the rains come and these plants put forth 
their conspicuous flowers, the deceit is at an end; but at this season a good deal of ephemeral vege- 
tation starts into rapid growth, and tender leaves and shoots would be more in demand than pretty 
flowers apparently springing from among rocky débris 
and pebbles. 
Photo by] LW. West. 
HOLLYHOCK. 
The pollen grains shown slightly enlarged in 
another photo are here magnified sixty-six times. 
They are covered with short spines, which cling 
to the hairs of insects. 
servatories. 
ments of rock. 
POLLEN 
BY EDWARD STEP, F.L.S. 
EVERYONE has noticed the yellow, meal-like powder 
which clusters around certain of the central organs of 
a flower, which the bee kneads up and packs into the 
hollowed part of her leg to carry home for feeding the 
grubs. Most of us know also that this is not the principal 
object the flower has in view when producing this pollen, 
and that its real purpose is the fertilization of the 
incipient seeds contained in the swollen base of the 
most central of all the flower organs. If a few grains 
of this powder are examined under the microscope 
Photo by] 
LW. West, 
EVENING PRIMROSE. 
The pollen grains are here magnified sixty- 
six times. They are triangular, with a pro- 
tuberance at each corner. Viscid threads attach 
them more securely to the heads of moths. 
every particle of it will be found to have a definite 
form, agreeing with all its fellows from that particular 
flower—though different species of flowers differ re- 
markably in the character of the pollen they produce. 
