164 THE FOREST LANDS OF NORTHERN RUSSIA. 
lines, the smallest diameter of which measures only the 
five-thousandth part of an inch. When perfect, the plant, 
as Dr Macmillan observes, bears a resemblance to a red- 
currant berry ; as it decays, the red colouring matter fades 
into deep orange, which is finally resolved into a brownish 
hue. The thickness of the wall of the cell is estimated at 
the twenty-thousandth part of an inch, and three hundred 
to four hundred of these cells might be grouped together 
in a smaller space than a shilling would cover. Yet each 
cell is a distinct individual plant; perfectly independent 
of others with which it may be massed: fully capable of 
performing for and by itself all the functions of growth and 
reproduction ; possessing “a containing membrane which 
absorbs liquids and gases from the surrounding matrix or 
elements, a contained fluid of peculiar character formed 
out of these materials, and a number of excessively minute 
granules equivalent to spores, or, as some would say, to 
cellular buds, which are to become the germs of new 
plants.” Dr Macmillan adds: “That one and the same 
primitive cell should thus minister equally to absorption, 
nutrition, and reproduction, is an extraordinary illustration 
of the fact that the smallest and simplest organised object 
is in itself, and, for the part it was created to perform in 
the operations of nature, as admirably adapted as the 
largest and most complicated.” 
‘The first vegetable forms to make their appearance at 
the limits of the snow-line, whether in high latitudes or 
on mountain-summits, are lichens ; which flourish on rocks, 
or stones, or trees, or wherever they can obtain sufficient 
moisture to support existence. Upwards of two thousand 
four hundred species are known. The same kinds prevail 
throughout the Arctic regions, and the species common 
to both the Eastern and Western hemispheres are very 
numerous. They lend the beauty of colour to many an 
Arctic scene which would otherwise be inexpressibly 
dreary ; the most rugged rock acquiring a certain air of 
picturesqueness through their luxuriant display. Their 
