Marvels of the Untverse 879 
of these are spherical, their surface bristling with points 
that enable them to cling to their carriers; but if any 
of them are brought into contact with the viscid stigma 
of the next flower visited the stickiness causes them to 
adhere there. The pollen-grain so detained sends out 
a tubular shoot which pierces the stigma, penetrates 
the whole length of the style, enters the ovary and 
unites with an ovule there. Its mission has been 
accomplished successfully. 
Some, instead of being spherical, are rather 
flattened and three-cornered, as is the case with that of 
the evening primrose ; others have the appearance of a 
cylinder spirally coiled upon itself ; some have chimney- 
like openings with lids; in some the surface is orna- 
mented with depressions like the cells of honeycomb. 
Viscid threads are attached to those of the evening prim- 
rose, which ensures their sticking more readily to the 
moths that carry them; and in the orchids similar 
threads from each grain unite to form a stalk ending in 
a sticky knob which adheres to the head of the insect. 
The buoyant, wind-borne type is shown in the pollen 
of Scots pine and cedar. It will be seen that the 
power of remaining suspended in the air for as long as 
possible is given by equipping the pollen-grain with 
two little air-bladders. 
THE CHEESE-MITE 
THE mite belongs to the lowest order of that group of 
animals which includes the spiders. Already numerous 
members of the family have been described in these 
pages, chief amongst them being the brilliant little 
Water-mites shown in the coloured plate opposite page 
763, and a large number of the ticks which infest birds 
and are first cousins to the mites. 
A mite, as we have seen, agrees with the spider in 
having eight legs ; but there is a considerable difference 
between the two in their earlier stages, for while the 
spider is born with all the characteristics of the parent, 
the mite, at its first appearance, has never more than 
six legs, and sometimes only four. It is hatched from 
an egg, and changes its appearance so remarkably 
during its career that the different forms of the same 
mite were at first classed as different species. It is the 
modern representative of an ancient race, for some of 
its progenitors are to be found royally entombed with 
the far-famed fly, in amber. 
The Cheese-mite belongs to the most important 
group of this family, all the members of which 
Photo by] [A. E. Smith. 
POLLEN. 
The pollen of the Mallow here shown is very 
similar to that of the related Hollyhock. 
Photo by] LW. West. 
HOLLYHOCK. 
The clustered stamens are shown with the anthers 
discharging the pollen. The round dots are the pollen- 
grains (shown ona larger scale in another photo). 
