Development and Distribution of Vegetation. 45 
sufficiently the time. It surely is no argument that such change has never 
taken place, because no difference can be detected since the time when the 
Egyptians first drew figures upon their obelisks and pyramids, or inclosed 
leaves and fruits in the sacred wrapping of their embalmed dead. This was 
but four or five thousand years ago—one and a half hours of man’s life-time, 
according to the comparison just made. 
However it is to be interpreted, the evidence is positive and unmistakable 
that very much change has taken place during the majestic eras in the history 
of plants. The rocks unerringly testify to a gradual development from low 
and simple forms to the more and more complex, ranking successively higher 
and higher in the recognized scale of organization and classification. Ina 
large majority of cases representatives of the various grades of the early 
plants continue to the present, overshadowed and belittled by. their successors 
and descendants. Such are the microscopic forms which in layers and crusts 
of innumerable individuals, tinge with green the old bark of trees, the sur- 
faces of old houses, fences and side-walks; those that form slimy scums on 
water; the mosses and ferns; the reeds and sedges of sloughs; the so-called 
ground pine of the mountains, and finally the coniferous or pine-like trees 
which still assert their position as prominent members of the flora of our 
times. 
For several reasons we are better acquainted with the plants of the coal 
measures than with any other of the geological periods. We cannot say how 
long since this luxuriant vegetation was embalmed in the form in which we 
now find it as coal, but the hundreds of thousands must rise into the millions 
and these again be several times repeated to express in terms of years the 
time which divides the age of the carboniferous rocks from the present. The 
time during which the coal itself was accumulating must have been very great, 
for a century scarcely suffices for the formation of a foot of humus by the 
rankest tropical vegetation of our time. In coal this is compressed to about 
one twenty-seventh of its thickness or less than half an inch. 
‘The flora of that old day was certainly wondrously different from that 
which we are permitted to investigate in the living state. The vegetation 
was rich enough in the masses of its product; but to our senses, accus- 
tomed as we are to the grandeur of trees, the beauty of flowers, the sweet 
fragrance of meadows, the appetizing lusciousness of orchards, the interesting 
and almost infinite variety of vegetable forms which now adorn and enrich 
the Earth — accustomed as we are to these, the dense but sombre and monot- 
onous vegetation of the coal period would strongly impress its gloominess 
upon us, and make us turn again with gratitude to the comparative para- 
dise we are given to dress and enjoy. ‘Then no beautiful flowers, enliv- 
ened by brilliant and varied colors or perfumed by sweet distillations, existed 
amid the rank and coarse leafage of the landscape. Not a single tree sim- 
ilar to our oaks, hickories, lindens, maples, apples, plums, lifted their leafy 
branches towards the sunlight; nor did anything in place of them bear nuts 
or fruits which would have tempted even our first mother Eve to try them. 
The coarse grass-like plants which then existed formed no pastures nor mead- 
ows. The Earth expanded its strength in the production of marsh-loving 
reeds and sedges, of club-mosses and ferns, with here and there a primitive 
pine-like and palm-like tree. Scouring rushes which, one to two feet high, 
to-day attract us by their peculiar structure, then rose in awkward proportions 
thirty or forty feet in height. Ferns waved their feathery foliage from the 
top of stump-like, brown trunks of equal altitude, while the club-mosses, of 
which our diminutive ground pine is a modern example, assumed the propor- 
tions of great forest trees. 
Various reptile-like amphibians of uncouth forms crawled lazily in the 
dense, moist shade, and peculiar insects winged their heavy flight through the 
